JP4338142B2 - Dental optical tomographic image display system - Google Patents

Description

  The present invention relates to an optical tomographic image display system for diagnosis or examination of periodontal disease and oral hard tissue.

(General)
As an index of the risk of developing lifestyle-related diseases represented by “Metabolic Syndrome”, abnormalities are discovered early by imaging / numerizing, that is, making the test values obtained through examinations and examinations objective. The idea of preventing onset is common in the medical community.
Although oral health has received much attention compared to before, objective diagnostic techniques have not progressed. Most oral diseases, such as caries and periodontal diseases, are considered lifestyle-related diseases. However, the diagnostic methods used in dental care are based on the idea of detecting abnormalities early and preventing their onset. Rather, it is common to find morphological abnormalities after onset. In oral examinations and screenings, definitive diagnoses such as early and appropriate periodontal disease diagnosis, hard tissue diagnosis, and oral soft tissue diagnosis are required, but many of the diagnostic techniques in dentistry are subjective diagnosis of dentists. Therefore, the diagnosis tends to depend on the skill and experience of the dentist. At present, X-ray examination is mainly used for diagnosis of dental diseases, but it is considered as one of diagnoses after the onset of abnormalities. While informed consent is regarded as important in the overall medical care, the current situation where subjective diagnosis is mainly used in the diagnosis of dental diseases has caused patients to increase their distrust in dental care. In addition, as represented by the “8020 Movement”, dental health examinations have received requests from society, but the results of subjective examinations by dentists as described above are not reliable, and local dental examinations and The current situation is that the dental checkup system has not become established as a corporate dental checkup and cannot meet the demands of society.
By using the present invention, intraoral diseases can be imaged and digitized, so that in terms of diagnosis, the diagnosis of dental diseases can be easily performed as an objective diagnosis rather than a dentist's subjective diagnosis. become. In terms of treatment, there is no false harm like X-rays, and it can be used frequently on the chair side, so that treatment can be performed faster, more accurately, more reliably, and the burden on the patient can be reduced. It becomes like this. In terms of the health checkup, it is possible to construct an oral health checkup system without difficulty, rather than a conventional dental checkup. Image information can be accurately provided to patients and can be effectively used for informed consent.
As described above, the present invention greatly contributes to diagnosis, treatment, and medical examination in dentistry.

(Periodontal disease)
In recent years, the relationship between periodontal diseases and systemic diseases such as aspiration pneumonia and endocarditis has been elucidated, and periodontal disease prevention itself has attracted attention not only for maintaining oral health but also systemic health . “Health Japan 21”, a national policy, aims to increase the population receiving periodontal disease prevention treatment such as calculus removal as a preventive measure for periodontal disease by 2011. Periodontal disease accounts for about half of the causes of tooth loss, and early treatment such as early diagnosis and removal of tartar is necessary for prevention. Prior to the treatment of periodontal disease, measuring the depth of the periodontal pocket in the gap between the tooth and gingiva has become an extremely important diagnostic criterion. At present, in measuring the periodontal pocket, a dentist inserts a search tool with a sharp tip into the periodontal pocket and subjectively measures the depth by visual inspection. This method is not only painful, but also hurts teeth and sometimes bleeds to exacerbate periodontal disease itself, and because of the contact type, there is also a risk of disseminating pathogenic bacteria between different teeth. In addition, since errors occur between the measurers, there are also aspects where accuracy and reproducibility are poor. Therefore, a non-contact, non-invasive device that objectively measures the depth of the periodontal pocket is required.

(Diagnosis of subgingival calculus)
With the progress of an aging society, the number of patients suffering from periodontal diseases is increasing. Periodontal disease gradually progresses, so the patient is less aware of the danger to the disease, destroying the periodontal tissue, eventually causing tooth movement and loss, resulting in a decrease in QOL. One of the treatments for periodontal disease is removal of tartar, but since tartar is likely to remain at the bottom of the periodontal pocket, the presence of deep tartar is hidden under the gums or bleeding, and the presence of the tartar is confirmed under direct viewing. Can not. On the other hand, in X-ray examination, it is difficult to specify the site of adhesion of calculus under the gingival margin, and there is a problem that exposure must be performed in a separate room for the problem of exposure and X-ray protection. Therefore, there is a need for a device that can easily check the site of attachment even with fine calculus in a non-contact and non-invasive manner.

(Caries diagnosis)
In caries treatment, it is one of the important factors that determine the prognosis of the treatment to accurately grasp and remove the range of caries. Conventionally, the clinical measurement has been made by direct observation with the naked eye and the operator's tactile sensation, but this is not an objective evaluation method. On the other hand, in the X-ray diagnosis that is widely used at present, it takes time for X-ray imaging, the problem of radiation exposure, and the need for shielding, so that it cannot be used frequently during medical treatment. was there. Further, even if X-ray imaging is performed, since the image is a two-dimensional transmission image, it has not been possible to accurately determine how far the dental caries has progressed.
Therefore, there is a demand for an apparatus capable of measuring a caries range that is high-resolution, non-invasive, can be three-dimensionally constructed, and does not require time. In particular, there is a need for an objective evaluation method that does not depend on the skill of the surgeon for mass screening.

(Determination of distance to dental pulp during caries treatment)
In dental caries treatment, the preservation of dental pulp is the first priority for cutting the erosion area of dental caries-causing bacteria, and therefore, careful consideration is given to the distance to the dental pulp. Conventionally, X-ray diagnosis that has been widely used has the drawbacks that X-ray imaging takes time, radiation exposure, and further shielding is necessary, so it cannot be used frequently during medical treatment. there were. Moreover, since the image is a two-dimensional transmission image even if X-ray imaging is performed, it is difficult to accurately measure the distance between the dental pulp and the cutting site. Therefore, a device that can measure the distance to the dental pulp non-invasively and easily during operation has been desired.

(Root canal length measurement)
Root canal treatment (dental pulp treatment) is the basis for subsequent crown restoration and prosthetic treatment. What is required in root canal treatment is accurate treatment up to the apex. The prognosis of treatment greatly deteriorates due to the remaining untreated portion of the apical pulp and the mechanical operation up to the so-called apical periodontal tissue beyond the apex. Therefore, measuring the length of the root canal and performing accurate treatment up to the apex is one of the important factors affecting the prognosis of treatment. Conventionally, measurement devices using X-ray photographs and electrical resistance have been used for the measurement, but X-ray imaging takes time and cannot be frequently used due to radiation exposure problems. was there. Further, since the image is a two-dimensional transmission image, it is difficult to accurately measure the length of the root canal. In addition, a measuring instrument using electrical resistance has a drawback that the measured value becomes inaccurate depending on the state in the root canal. Therefore, an apparatus that can accurately measure the root canal length by acquiring an image of the apex easily with good resolution during the operation is desired.

(Dental fracture diagnosis)
One of the traumas caused by traffic accidents and sports is the facial part of the trauma. Also, it is common in dental practice that tooth cracks and fractures occur after root canal treatment leading to extraction. Conventionally, X-ray imaging has been performed for the diagnosis, but there are drawbacks that it takes time and cannot be frequently used because of the problem of radiation exposure. In addition, since the X-ray diagnostic image is a two-dimensional image, the tooth breakage in the horizontal direction is depicted on the X-ray image, but for the tooth breakage in the vertical direction, the break line is the same as the X-ray incident direction. If it is not done, it will not be drawn on the image and it will be difficult to diagnose. Therefore, even if an image is taken, an image useful for diagnosis is not always obtained. Therefore, there is a need for a diagnostic apparatus that can accurately and immediately and non-invasively measure the site of a broken tooth and the direction of the broken line by searching for a broken tooth from all directions during medical treatment.

(Intraosseous cyst (apical foci) diagnosis)
After root canal treatment, apical lesions and cystic diseases frequently occur. Conventionally, diagnosis of intraosseous cysts (apical lesions) includes X-rays, CT scans, and histopathological examinations. In X-rays and CT, in addition to the time required for imaging, there were problems with X-ray exposure. Furthermore, since the X-ray photograph is acquired as a two-dimensional image, it does not reach the buccal tongue position of the cyst, and a CT must be taken for detailed examination. CT also uses X-rays and requires a radiation dose several times that of simple X-ray photographs. Therefore, in addition to X-ray photography, the patient is exposed to radiation. In addition, in the histopathological examination, there is an invasion of adding a scalpel to a living body, and there is a disadvantage that a period from tissue collection to diagnosis is long. In addition, there is a drawback in that there is a high risk of postoperative pain, inflammation, infection, etc. around the lesion at the time of tissue collection. Therefore, there is a need for an apparatus capable of making a diagnosis with high resolution, non-invasively, and immediately including accurate positioning of intraosseous cysts (apical lesions).

(Oral cancer and oral mucosal disease diagnosis)
Cancer is the top cause of death in Japan and a major social problem. Of these, oral cancer accounts for about 10% of all cancers and develops at a relatively high frequency. Sometimes, these diseases can be life-threatening. Early detection, early diagnosis, and early treatment are required. Conventionally, macroscopic diagnosis and histopathological diagnosis have been performed in the diagnosis. There is a drawback that macroscopic diagnosis is difficult to distinguish from healthy tissue and early diagnosis is not possible unless considerable changes are observed. On the other hand, histopathological diagnosis requires a long period of time from tissue collection to diagnosis, as well as risks such as anesthesia during tissue collection, invasiveness by excision, seeding of cancer cells, postoperative pain around the lesion, inflammation, infection, etc. There was also a disadvantage that was large. Therefore, in order to achieve the principle of early detection and early diagnosis, a device capable of diagnosing oral cancer and oral mucosal disease with high resolution, simply, non-invasively and immediately is required.

(Xerostomia, small salivary gland diagnosis)
With the advent of a declining birthrate and aging society, the number of elderly people requiring care is increasing, but in those elderly people requiring care, xerostomia is often observed, leading to local and systemic infections and causes of eating and swallowing dysfunction. It has become. Conventionally, this diagnosis has been performed mainly by contrast X-ray imaging, ultrasonic image diagnosis, and pathological biopsy. In contrast X-ray imaging, there is a risk of side effects due to intravenous injection of contrast medium, in addition to the time required for imaging, X-ray exposure problems. Ultrasound can acquire an image non-invasively, but the resolution is poor. In particular, an image of a small salivary gland is difficult to distinguish from a healthy tissue. As a result, it is left to histopathological diagnosis, but it has the disadvantages that bothersome work is required and the period until diagnosis is long. In addition, there are drawbacks such as anesthesia when collecting glandular tissue, invasiveness by excision, and postoperative pain, inflammation, infection, etc. around the excision area. There is a need for an apparatus capable of diagnosing the histological morphology and properties of a small salivary gland with high resolution, simply and non-invasively.

(Tongue pain diagnosis)
There have been some reports of so-called unknown diseases that complain of some symptoms (including indefinite complaints) despite the absence of organic changes in each part of the body. Some of these diseases are also found in the oral cavity area, but one of them is no systemic or local organic disorder, and the cause of burning pain on the tongue is unknown. Chronic morbidity is often seen. The description in Japan is reported to have been reported about this disease from around 1970, but although it is common among middle-aged and older women, no clear pathology has yet been identified. Since there are no abnormalities in organic disorders and various examinations, diagnostic criteria and treatment methods have never existed. Therefore, by acquiring images of the tongue instantly with high resolution and non-invasiveness, we found some organic changes in the tongue that could not be grasped on the images, and established a method for diagnosing glossodynia. It is requested to do.

(Soft tissue cyst)
Occasionally, soft tissue in the oral cavity has a bag-like lesion that contains a liquid component called a cyst. Conventionally, the diagnosis has been performed histopathologically. This method has a drawback that it takes a long period of time until diagnosis, and is invasive due to anesthesia and excision at the time of tissue collection, as well as postoperative pain around the lesion, inflammation, infection, and the like. Removal is a common treatment for soft tissue cysts. Since the anatomy of the oral cavity is extremely complex, not only the depth and width of the lesion prior to surgery, but also the positional anatomy such as blood vessels in the excised area, vascular nervous system such as nerves, and muscle tissue It must be evaluated accurately. Accordingly, there is a need for an apparatus that can evaluate a lesion or surrounding positional anatomy and diagnose soft tissue cysts with high resolution and non-invasiveness immediately.

  In Non-Patent Document 1, as a device for obtaining a tomographic image, light from a light source is branched and one of them is used as reference light, the reference light is reflected by a reference mirror, and the other branched signal light is irradiated to an object. Scattered light and reference light are caused to interfere with each other by a beam splitter. A signal having a structure in the depth direction is obtained by changing the position of the reference mirror of the reference light. A diagnostic apparatus based on optical coherent tomography (hereinafter simply referred to as OCT) in which a cross-sectional image is obtained by scanning signal light has been proposed.

Further, in Patent Document 1, when OCT is applied to a dental apparatus, light is branched using a low-coherent light source, one is irradiated to a reference mirror, and the other is irradiated to a measurement object. Then, after making the obtained light interfere with the reference light, it is incident on the diffraction grating and demultiplexed, and the reflected light from the diffraction grating is received by a one-dimensional or two-dimensional CCD camera. Also, there is a device in which a galvanometer is incorporated in the probe to scan light, a mechanical quantity sensor is provided, the momentum is measured by the mechanical quantity sensor, the scanning amount of the probe is recognized based on this, and an image signal is obtained. Proposed.
DAVID HUANG et al. “Optical Coherence Tomography” SCIENCE, NOVEMBER 1991 VOL. 254 PP1178-1181 JP 2006-132955 A

  However, in the conventional OCT of Non-Patent Document 1, it is necessary to change the position of the reference light in order to obtain a signal from the light irradiation direction, which has a drawback that the structure becomes complicated. In the OCT of Patent Document 1, the interferometer exists outside the probe, and the interferometer and the probe are connected by an optical fiber. Therefore, in order to keep the difference between the optical path length to the reference mirror and the optical path length to the detector depending on the length of the optical fiber within the excessive interference distance range, a mechanism for adjusting the optical path length difference in the middle of the interferometer is required. In addition, there is a drawback that it is necessary to adjust the polarization plane of the fiber from the interferometer device side to the probe.

In order to solve this problem, the dental optical tomographic image display system of the present invention irradiates a subject with a scanning light source that periodically scans the oscillation wavelength of light, and emission light obtained from the scanning light source. A probe that sweeps while scanning, a light receiving element that obtains a beat signal from the interference light of the light received by the probe, a first optical fiber that guides at least light of the scanning light source to the probe, and light received by the probe A second optical fiber for guiding the interference light of the light to the light receiving element, and a Fourier transform of the light receiving signal obtained in the light receiving element in synchronization with the oscillation of the equal frequency of the light of the scanning light source, and from the probe An image signal processing unit that generates a tomographic image of teeth and gums by being arranged according to the emission of the probe, wherein the probe is obtained from the first optical fiber. An interferometer that includes a branch mirror that branches light from the light source into outgoing light and reference light, emits outgoing light to the subject, and interferes with scattered light from the subject and the reference light; and the branch A position where the outgoing light branched by the mirror is swept toward the subject and the relative movement between the probe and the subject is detected, and a deflecting unit that makes the scattered light from the subject incident on the interference optical meter And the signal processing unit generates a three-dimensional cross-sectional image based on an output from the position sensor.

  Here, the deflection unit of the probe includes a motor and a mirror that is attached to the rotation shaft of the motor and reflects the emitted light, and the probe guides the emitted light to the outside and receives the reflected light. The signal processing unit may obtain a synchronization signal based on a change in the interference light signal obtained at the opening end of the probe.

  Here, the deflection unit of the probe is a MEMS scanner, and further includes a trigger mirror that reflects light in the same direction at an end of light scanned by the MEMS scanner, and the signal processing unit includes the mirror The trigger signal may be obtained on the basis of the light reception signal reflected by the.

  Here, the position sensor may be a laser mouse position sensor.

  Here, the position sensor may use any one of a potentiometer, an optical encoder, and a position detection element (PSD).

  According to the present invention having such a feature, an interferometer is built in the probe, the oscillation wavelength is swept using a wavelength scanning light source, the reflected light is made to interfere with the reference light, and the interference light is Fourier transformed. By performing the conversion, a distribution in the depth direction can be obtained and a tomographic image can be displayed. Therefore, unlike the non-patent document 1, it is not necessary to modulate the optical path length by changing the reflection position of the reference light. Further, since the distance from the probe to the detected object and the arrangement of the reference light are fixed within the probe, it is not necessary to adjust the optical path length difference. Therefore, there is no effect that the polarization plane is not fluctuated by the movement of the probe and the signal does not fluctuate.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an optical tomographic image display device according to a first embodiment of the present invention. In FIG. 1, a light source 11 is a wavelength scanning type light source that periodically sweeps a single spectrum optical signal in a predetermined wavelength range. Light from the light source 11 is given to the optical circulator 13 through the optical fiber 12. The optical circulator 13 outputs an optical signal incident on the terminal 13a to the terminal 13b and an optical signal incident on the terminal 13b to the terminal 13c. One ends of optical fibers 14 and 15 are connected to the terminals 13b and 13c, respectively, and a probe 16A is provided on the other end of the optical fiber 14. As will be described later, an interference optical meter is formed inside the probe 16A, and the probe 16A sweeps while irradiating the object to be detected and receives the scattered light. The ends of the optical fiber 15 connected to the terminal 13c of the optical circulator 13 and the other optical fiber 17 connected from the probe 16A are connected to a balanced receiver (BR) 18, respectively. The balanced receiver 18 converts a difference signal between two optical signals whose phases are inverted into an electric signal. The output of the balanced receiver 18 is given to a low pass filter (LPF) 20 through an amplifier 19. The output of the low-pass filter 20 is given to the AD conversion unit 21. The AD conversion unit 21 performs AD conversion on the output of the low-pass filter based on the output from the trigger generation unit 22. The signal processing unit 23 is an image signal processing unit that obtains information in the scanning direction by Fourier-transforming the AD conversion output at equal wavelength intervals. Further, information on the scanning direction is obtained based on an output from a position sensor, which will be described later, and is displayed on the image display unit 24 as a two-dimensional image.

  The light source 11 described above is a laser light source that oscillates an optical signal having a single spectrum. For example, a wavelength scanning fiber light source disclosed in Japanese Patent Application Laid-Open No. 2006-80384 is used. Here, as the oscillation wavelength, it is preferable to use, for example, a 1.3 μm band in which water absorption is small and scattering is small. The wavelength scanning range is, for example, 100 nm to 200 nm, and the sweep speed is, for example, 20 kHz.

  2 is a longitudinal sectional view showing the configuration of the probe 16A, and FIG. 3 is a sectional view taken along the line AA. The probe 16A includes a handle portion 31a and a sensor portion 31b. Both the handle portion 31a and the sensor portion 31b are cylindrical casings, and the longitudinal direction is the Z axis as shown in the figure. In the sensor unit 31b, a collimator lens 33 that converts the light emitted from the optical fiber 14 into parallel light in the Z-axis direction, and an optical block 34 that reflects the output from the collimator lens 33 are provided. As shown in the drawing, mirrors 35 and 36 are arranged perpendicular to each other at an angle of 45 ° with respect to the Z axis, and a half mirror 37 is arranged in parallel to the mirror 35 therebetween. A lens 38 and a reference mirror 39 are provided at the front end of the optical block 34 perpendicular to the Z axis. A collimating lens 40 is provided on the optical axis via a half mirror 37, and the above-described optical fiber 17 is connected to the collimating lens 40. A rotating mirror 41 is provided at a position for receiving the light reflected by the mirror 36. As shown in the figure, the motor 42 has a rotating mirror 41 mounted at an angle of 45 ° with respect to its axis, and drives the rotating mirror 41. The rotating mirror 41 reflects light incident upon rotation of the motor 42 in one direction on the XY plane at an angle of 360 °. A transparent window 31c is provided on the side of the sensor unit 31b at a position where light is emitted from the lens 43. A lens 43 is provided in the vicinity of the window 31c. The lens 43 is a condensing lens that irradiates light in a certain angle range of the reflected light in parallel with the X axis as shown in FIG. 3 and collects scattered light from the detected object. Here, the collimating lenses 33 and 40, the mirrors 35 and 36, the half mirror 37, the lens 38, and the reference mirror 39 constitute an interference optical meter.

  Next, the principle of optical coherent tomography using a scanning light source will be described. The target object is irradiated with coherent light having a single spectrum whose wavelength continuously and periodically changes from the light source 11 and reflected inside the object or the subepidermal layer using a coherent optical meter such as Michelson or Mach-Zehnder. The backscattered light and the reference light are caused to interfere with each other. Tomographic information along the depth direction (X direction) can be obtained by measuring the intensity change of the interference light with respect to time and obtaining the intensity distribution of the optical wavelength component by Fourier transforming it. It can be output to the image display unit 24 as an image signal.

  Next, the operation of the first embodiment will be described. First, as shown in FIG. 4, the probe 16A is fixed, for example, toward the gingival part of the front tooth. The light source 11 continuously scans the oscillation wavelength λ at a constant period as shown in FIG. 5A. As shown in FIG. 5B, a trigger signal is obtained from the trigger generator 22 every time the sweep is started. Now, the light from the light source 11 enters the probe 16A via the optical fiber 12 and the optical circulator 13. In the probe 16 </ b> A, light in the Z-axis direction from the collimating lens 33 is reflected by the mirror 35 and is incident on the half mirror 37. The light reflected here enters the reference mirror 39 as reference light, is reflected in the same direction as it is, and returns to the half mirror 37.

  On the other hand, the light transmitted through the half mirror 37 is reflected again by the mirror 36 and enters the rotating mirror 41. By rotating the rotating mirror 41, light parallel to the X axis is irradiated to the anterior gingival portion only during a period of 360 ° passing through the transparent window 31c, as shown in FIG. The irradiation position is swept in the Y-axis direction by the rotation of the motor 42. The light incident on the teeth and gingiva is scattered inside, and part of it returns to the incident side. 6A and 6B are different in time axis from FIGS. 5A and 5B, FIG. 6A is a graph showing scanning in the Y-axis direction, and FIG. 6B shows the signal intensity of the scattered light obtained at that time. Yes. The scattered light is reflected by the mirrors 41 and 36 via the condenser lens 43, and interferes with the reference light by the half mirror 37 to obtain interference light. The interference light enters the balanced receiver 18 through the collimator lens 40 and the optical fiber 17 and through the mirror 35, the collimator lens 33, and the optical fiber 14, and enters the balanced receiver 18 to be converted into an electrical signal. Is done. Now, since this interference light is obtained intermittently as shown in FIG. 6B, a trigger signal of one frame can be obtained based on the rise of this signal. This electrical signal is filtered by the low-pass filter 20, and as described above, the interference signal obtained for the sweep of one wavelength is AD-converted and Fourier-transformed at equal wavelength intervals to obtain a one-dimensional intensity distribution. This intensity distribution is converted into a gray scale to obtain a depth signal of one line in the X direction or an OCT image signal. Then, by repeatedly acquiring the OCT signals in the Z direction at different positions in the Y direction according to the rotation of the motor 42, the light beam is further scanned in the Y direction along the surfaces of the teeth and the gingiva, A two-dimensional image can be displayed on the image display unit 24. In this case, an image signal for a predetermined frame may be stored in an image memory (not shown), and noise may be removed by averaging or the like.

  FIG. 7 is a diagram showing an example of the cross-sectional image created in this way. Based on this cross-sectional image, it is possible to visually measure the health condition of the teeth, particularly the depth of the periodontal pocket. Note that the scanning speed of the wavelength of the scanning light source 11 is preferably about 100 times or more, more preferably several hundred times or more the scanning speed in the Y direction of the probe 16A.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a block diagram showing the overall configuration of this embodiment. The same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In this embodiment, a laser position sensor 51 is provided on the probe 16B as will be described later. The laser position sensor 51 is a position sensor that outputs a relative position signal of the probe 16 </ b> B, and the output is given to the signal processing unit 25. The signal processing unit 25 generates a three-dimensional image based on the output from the AD conversion unit 21, the trigger signal from the trigger generation unit 22, and the position signal, and outputs the three-dimensional image to the image display unit 24.

  FIG. 9 is a block diagram showing the configuration of the probe 16B according to the second embodiment. In this figure, in addition to the configuration described above, a laser position sensor 51 is provided in the sensor unit 31b. 10A and 10B are diagrams showing the relationship between the detailed configuration of the position sensor and the fixing portion fixed to the teeth. When the laser position sensor 51 is used, the support portions 52a and 52b are fixed to the side surfaces of the teeth as shown in FIG. A joint portion 53 is provided between the support portions 52a and 52b and the probe 16B so that the probe 16B can move along the Z-axis direction. The laser position sensor 51 includes a laser 54, a two-dimensional CCD sensor 55, and a signal processing unit 56. The laser 54 irradiates the surface of the support portion 51a with light, and the CCD sensor 55 receives the reflected light. Then, by comparing a plurality of images from the CCD sensor 55 obtained at different timings, a relative position signal of the probe and the measurement object is output. As the laser position sensor, a sensor put into practical use as a laser mouse sensor can be used as it is. This position signal is given to the signal processor 25 as a digital signal. In this way, the signal processing unit 25 can generate and display a three-dimensional image by combining scanning in the XY plane by the motor 42 and scanning in the Z-axis direction.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the same parts as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the third embodiment, the probe 16C uses a position sensor 61 by an optical encoder instead of the laser position sensor 51.

  Next, the position sensor 61 will be described with reference to FIGS. 11A and 11B. Also in this embodiment, as shown in FIGS. 11A and 11B, support portions 52a and 52b are attached to the side surfaces of the teeth and fixed. A joint portion 53 is provided in the support portion and the sensor portion of the probe to move the probe 16C along the Z-axis direction. The position sensor 61 has a laser 62 as a light projecting unit and a driver (not shown) that drives the laser 62, and is configured to irradiate light to the scale plate 63 of the support unit 52a from the laser 62. On the scale plate 63, a pattern of a highly reflective portion and a non-reflected portion having high reflectivity are alternately carved with a resolution of several tens of μm. A photodiode 64 is provided at a position where the reflected light from the scale plate 63 is received, and a signal processing unit 65 is provided at the output end thereof. The signal processing unit 65 has an amplifier that amplifies and shapes the output from the photodiode 64 and a counter that counts the number of output pulses. The count output of the counter is output as a digital position signal.

  Here, when the probe 16C is moved in the Z-axis direction, the light irradiated from the laser 62 of the optical encoder enters the scale plate 63, and the reflectance becomes “0”, “1” pattern to the photodiode 64. Received light. Accordingly, the position signal can be obtained from the counter of the signal processing unit 65 by shaping the waveform of the output and multiplying it as necessary to count the number of pulses. Further, instead of the laser 62 and the photodiode 64, light may be incident from the outside of the probe through a fiber, and the signal processing unit 65 may be provided outside the probe. In this case, since no electrical wiring is required for the probe, it is effective in preventing a short circuit due to saliva in the mouth and an electric shock.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the same parts as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the fourth embodiment, a probe 16D is provided with a potentiometer position sensor 71 instead of the laser position sensor 51, as will be described later.

  Next, the position sensor 71 will be described with reference to FIGS. 12A and 12B. Also in this embodiment, as shown in FIGS. 12A and 12B, support portions 52a and 52b are attached to the side surfaces of the teeth and fixed. A joint portion 53 is provided on the support portion and the sensor portion of the probe, and the probe 16D is moved along the Z-axis direction. In order to detect the position in the Z-axis direction, the potentiometer 72 is arranged parallel to the Z-axis as shown in the figure, and the operation pin 73 of the potentiometer is fixed to the joint portion 53. In this way, by applying a voltage to both ends of the potentiometer 72, the position of the probe in the Z-axis direction can be detected based on the voltage signal from the middle point.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the same parts as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the fifth embodiment, a PSD position sensor 81 is provided instead of the laser position sensor 51.

  Next, the position sensor 81 will be described with reference to FIGS. 13A and 13B. Also in this embodiment, as shown in FIGS. 13A and 13B, the support portion 52a is attached to the side surface of the tooth and fixed. A joint portion 53 is provided in the support portion and the sensor portion of the probe so that the probe 16E can move along the Z-axis direction. And PSD82 is arrange | positioned on the support part 52a for a position detection. A laser 83 is attached to the probe 16E so as to enter the PSD 82. Further, the current output ends of both ends of the PSD 82 are led to the probe 16E via the connector of the joint portion 53, and are output to the signal processing portion 86 so as to absorb the interval by the lead wire 85 via the slide type connector 84. ing. The signal processor 86 outputs a position signal based on the current output ratio. In the state shown in FIG. 13A, the light from the laser 83 is incident on the right end of the PSD 82, and in the state where the probe 15E is moved to the leftmost, the light is incident on the left end of the PSD 82 as shown in FIG. 13B. Accordingly, the position of the probe in the Z-axis direction can be detected based on the incident position on the PSD 82.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In this embodiment, the probe 16F is provided with a deflecting unit using a MEMS actuator instead of the deflecting unit using the motor 42 and the reflecting mirror 41. A voltage source 26 is connected to the probe 16F. The output of the low-pass filter 20 is connected to the AD converter via the discriminator 27. The discriminating unit 27 gives a high level signal exceeding the threshold value to the signal processing unit 28 as a trigger signal. The signal processing unit 28 performs Fourier transform using this trigger signal as a temporal symmetry axis. Other configurations are the same as those of the first embodiment.

  FIG. 15 is a cross-sectional view showing the configuration of the probe 16F of this embodiment. In this embodiment, a MEMS actuator is used instead of the motor 42 and the mirror 41. As shown in FIG. 14, the MEMS actuator 91 is provided at a position of the mirror 41 so as to be inclined by 45 ° with respect to the Z-axis direction. The MEMS actuator 91 deflects the light reflected by the mirror 36 in the XY plane, and is added to the lens 43. This light is irradiated in the X-axis direction by the lens 43. Therefore, unlike driving by a motor, scattered light can be obtained without any breaks.

  Next, the MEMS actuator 91 will be described in more detail. 16 is a perspective view of the MEMS actuator 91, and FIG. 17 is a cross-sectional view thereof. As shown in these drawings, in the MEMS actuator 91, electrodes 93a and 93b are formed on a base 92, and spacers 94a and 94b are formed on the sides of the electrodes. A tilt mirror 96 is rotatably attached to the spacers 94a and 94b on the electrodes 92a and 92b via hinges 95a and 95b. The axis passing through the center of the hinge and tilt mirror of the tilt mirror 96 is an axis parallel to the Y axis. As shown in the figure, the voltage source 26 is connected between the lower electrode 93b and the tilt mirror 96.

  When an AC voltage is applied from the voltage source 26, the tilt mirror 96 is rotated by electrostatic attraction based on the voltage, whereby reflected light from the mirror 36 is reflected by the tilt mirror and scanned on the XY plane. Further, this light is emitted to the outside through the condenser lens 43 in parallel with the X axis as shown in FIG. In this case, as shown in FIG. 18A, the position in the Y-axis direction is scanned in a triangular wave shape, and scattered light corresponding to the position is obtained. By arranging a trigger mirror 97 at the end of the light scanning range as shown in FIG. 16, when the light scans this position, a high level output is obtained as shown in FIG. 18B. . Therefore, a frame trigger signal can be obtained from the discriminating circuit 27 using a predetermined high level as a threshold value.

  In each of the above-described embodiments, the interference light from the probe is guided to the balanced receiver 18 by the two optical fibers 15 and 17 and converted into an electrical signal. Alternatively, the light from the light source 11 may be incident on each probe via the optical fiber 12, and the interference light may be converted into a received light signal by a photodiode via a single optical fiber. In this case, since only the photodiode is sufficient instead of the optical circulator 13, the optical fiber 15, and the balanced receiver 18, the configuration can be simplified.

  Moreover, in each embodiment, although the probe united the handle | steering-wheel part and the sensor part, the sensor part can be attached or detached with respect to a handle | steering-wheel part, and can be used as a disposable sensor part for every patient.

The present invention performs a dental examination by using a scanning light source and providing a trigger circuit suitable for the image display system. By using this device,
(1) Periodontal disease diagnosis Periodontal pocket inspection Tartar image that cannot be judged with the naked eye (2) Hard tissue diagnosis Caries diagnosis 2. Distance inspection to dental pulp Measurement of root-knot length 4. 4. Dental fracture diagnosis Diagnosis of intraosseous cyst (apical lesion) (3) Diagnosis of oral disease Oral tumor and oral mucosal disease (diagnosis of benign tumor and malignant tumor and diagnosis of precancerous disease)
(4) Soft tissue diagnosis Small salivary gland Tongue pain 3. It can be used for diagnosis of various diseases such as soft tissue cysts.
By utilizing such a diagnostic technique of the present invention, it becomes possible to embody an oral health diagnostic system that could not be systematized. Furthermore, it is not limited to dental use, and any portion having a relatively hard fixed portion and capable of measuring a relative position with respect to the fixed portion can be widely and effectively used for their cross-section and tomographic measurement. .

1 is a block diagram showing an overall configuration of a scanning optical tomography display system according to a first embodiment of the present invention. It is sectional drawing of the probe by this Embodiment. It is AA sectional view taken on the line of the probe by this Embodiment. It is a figure which shows the scanning of the light by this Embodiment, and the gingival part used as a measuring object. It is a graph which shows the change with time of the oscillation wavelength of the light source 11. It is a figure which shows the trigger signal from the trigger generation part 22. FIG. It is a figure which shows the time change of the scanning position of light. It is a figure which shows the change of the reflected light obtained corresponding to the scanning of light. It is a figure which shows an example of the tomographic image of the display system by this Embodiment. It is a block diagram which shows the whole structure of the scanning optical tomography display system by the 2nd Embodiment of this invention. It is sectional drawing of the probe by this Embodiment. It is a figure which shows the position sensor by the 2nd Embodiment of this invention. It is a figure which shows the position sensor by the 2nd Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 3rd Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 3rd Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 4th Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 4th Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 5th Embodiment of this invention. It is a figure which shows the structure of the position sensor by the 5th Embodiment of this invention. It is a block diagram which shows the whole structure of the scanning optical tomography display system by the 6th Embodiment of this invention. It is sectional drawing of the probe by the 6th Embodiment of this invention. It is a perspective view which shows operation | movement of the MEMS actuator by this embodiment. It is sectional drawing of the MEMS actuator by this embodiment. It is a perspective view which shows the time change of the scanning position of the light at the time of using a MEMS actuator. It is a figure which shows the change of the scattered light obtained corresponding to the scanning of light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12, 14, 15, 17 Optical fiber 12, 20 Lens 13 Optical circulator 14, 17 Coupling part 16 Interferometric optical meter 16A-16F Probe 18 Balanced receiver 20 Low-pass filter 21 AD conversion part 22 Trigger generation part 23 Signal processing part 24 Image display unit 33, 40 Collimator 34 Optical block 35, 36 Mirror 39 Reference mirror 41 Rotating mirror 42 Motor 43 Condensing lens 51, 61, 71, 81 Position sensor 52a, 52b Support unit 53 Joint unit 54, 62 Laser 55 CCD
56, 65, 85 Signal processor 63 Scale plate 64 Photodiode 72 Potentiometer 73 Operation pin 82 PSD
91 MEMS actuator 96 Tilt mirror 97 Trigger mirror

Claims (5)

A scanning light source that periodically scans the oscillation wavelength of light;
A probe that sweeps while irradiating a subject with emitted light obtained from the scanning light source;
A light receiving element for obtaining a beat signal from the interference light of the light received by the probe;
A first optical fiber for guiding at least light from the scanning light source to the probe;
A second optical fiber that guides interference light of light received by the probe to the light receiving element;
A tomographic image of teeth and gums is obtained by Fourier-transforming the received light signal obtained by the light receiving element in synchronization with the oscillation of the equal frequency of the light of the scanning light source, and arranging it according to the emission from the probe. An image signal processing unit for generating
The probe is
A branching mirror for branching the light of the scanning light source obtained from the first optical fiber into outgoing light and reference light; emitting the outgoing light to the subject; and scattered light from the subject and the reference An interferometer that interferes with the light;
A deflecting unit that sweeps outgoing light branched by the branch mirror toward the subject, and makes scattered light from the subject enter the interference optical meter;
A position sensor for detecting a relative movement amount between the probe and the subject,
The said signal processing part is a dental optical tomographic image display system which produces | generates a three-dimensional cross-sectional image based on the output from the said position sensor. The deflection part of the probe is
A motor,
A mirror that is attached to the rotating shaft of the motor and reflects the emitted light;
The probe has an opening for guiding outgoing light to the outside and receiving reflected light,
The dental optical tomographic image display system according to claim 1, wherein the signal processing unit obtains a synchronization signal based on a change in an interference light signal obtained at an opening end of the probe. The deflection part of the probe is
A MEMS scanner,
A trigger mirror that reflects light in the same direction at the end of the light scanned by the MEMS scanner;
The signal processing unit
The dental optical tomographic image display system according to claim 1, wherein a trigger signal is obtained based on a light reception signal reflected by the mirror. The position sensor is
Dental optical tomographic image display system according to claim 1, wherein the position sensor laser mice. The position sensor is
Potentiometer, dental optical tomographic image display system of claim 1 wherein using one of the light encoder, the position detection element (PSD).

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