JP5577513B2 - Reference grating, method of using the reference grating, and optical coherence tomography diagnostic apparatus including the reference grating - Google Patents

Description

  The present invention relates to a reference grating suitable for performing optical coherence tomographic image diagnosis with high accuracy, a method of using the reference grating, and an optical coherence tomographic image diagnosis apparatus including the reference grating.

  In dentistry, teeth are treated by loading restorations and prostheses into the cavities formed in the teeth. In order to obtain information on the shape of the cavity formed in the tooth and in the oral cavity, an indirect model of the tooth or oral cavity is created using an impression material (eg, plaster, agar, alginate, rubber, silicone). Then, a restoration / prosthesis is created using the indirect model as a mold.

  However, until the acquisition of morphological information on teeth, such as acquisition of morphological information such as teeth by impression material, creation of an indirect model based on the impression material, creation of a restoration / prosthesis using the indirect model as a mold Since it has undergone a plurality of steps, various medical resources are consumed and it may take time.

  Therefore, Patent Document 1 discloses an optical coherence tomographic image diagnosis (optical coherence tomography (OCT), hereinafter referred to as “OCT”) apparatus that can easily and quickly acquire morphological information.

JP 2006-280449 A

  However, since a part of the OCT image acquired by OCT is an image based on a calculated value obtained from a predetermined algorithm, the OCT image may be different from the actual size. Accordingly, there is a need for a new technique suitable for performing optical coherence tomographic image diagnosis with high accuracy.

  The present invention has been made in view of the above problems, and provides a reference grid suitable for accurately performing optical coherence tomographic image diagnosis, a method of using the reference grid, and an optical coherence tomographic image diagnostic apparatus including the reference grid. The purpose is to provide.

In order to achieve the above object, the reference grating according to the first aspect of the present invention is:
A reference grid used for diagnosis of optical coherence tomographic images,
It consists of a member that transmits light,
The member comprises a plurality of grid lines,
The reference grating is measured together with the object displayed in the optical coherence tomographic image,
The plurality of grid lines are displayed in the optical coherence tomographic image.
It is characterized by that.

  It is also possible that the interval between the grid lines is predetermined at a predetermined distance.

  The grid lines may be arranged in a grid pattern.

The method of using the reference grid according to another aspect of the present invention is as follows:
Fixing the reference grating on the object,
Irradiate the fixed reference grating and the object with low interference light, and measure the reference grating and the object based on the reflected light obtained by reflecting the low interference light by the reference grating and the object. ,
Identifying an error included in the measured dimension of the measured object based on the difference between the measured dimension between the grid lines of the measured reference grid and the actual dimension between the grid lines;
It is characterized by that.

  It is also possible to correct the identified error and display an optical coherence tomographic image based on the corrected measurement dimension of the object.

An optical coherence tomographic image diagnostic apparatus comprising a reference grating according to another aspect of the present invention,
Irradiated with low coherent light to the reference grating and the object, and the reference grid the low interference light by and the object based on the reflected light which is reflected, measuring unit for measuring the reference grating and the object ,
A storage unit for storing actual dimensions between grid lines included in the reference grid;
A correction unit that corrects an error included in the measured dimension of the measured object based on a difference between a measured dimension between grid lines included in the measured reference grid and an actual dimension between the grid lines;
And a display unit for displaying an optical interference tomographic image based on the measurement size of the corrected object,
It is characterized by that.
The measurement unit may include the reference grating at a tip for irradiating the low interference light.

  According to the present invention, optical coherence tomographic image diagnosis can be performed with high accuracy.

It is a figure for demonstrating the measurement principle of OCT. It is a figure for demonstrating the measurement principle of OCT. It is a block diagram which shows the whole structure of the wavelength scanning type optical tomography display system by which OCT is implement | achieved. It is a figure which shows an example of the measurement result by OCT. It is a figure which shows the irradiation method of light. It is a figure which shows distortion of a target object. It is the figure which compared the real image and OCT image of a tooth. It is a figure which shows schematic structure of a reference | standard grating | lattice. It is sectional drawing in the AA of FIG. It is sectional drawing in the AA of FIG. It is a figure for demonstrating the installation position of a reference | standard grating | lattice. It is a figure for demonstrating the usage method of a reference | standard grating | lattice. It is an example of the OCT image containing a reference | standard grating | lattice. It is an example of the OCT image after correction | amendment. It is a figure which shows schematic structure of an optical coherence tomography diagnostic apparatus. It is a figure which shows a measurement part provided with a reference | standard grating | lattice. It is a flowchart for demonstrating the image correction process performed with an optical coherence tomography diagnostic apparatus. It is a figure which shows the modification of a reference | standard grating | lattice. It is a figure which shows the modification of the cross section in the AA of FIG.

  Hereinafter, one of the embodiments of the present invention will be described. However, the embodiment is for facilitating understanding of the principle of the present invention, and the scope of the present invention is limited to the following embodiments. Instead, other embodiments in which those skilled in the art appropriately substitute the configurations of the following embodiments are also included in the scope of the present invention.

  The reference grating according to the present embodiment is used when measuring by optical coherence tomography (OCT) capable of diagnosing a living tissue using optical information inside the tissue.

  The OCT apparatus is an apparatus that can measure a tissue in a living body on a micro order with extremely high resolution. In OCT, by using a near-infrared light source that can reach below the body surface, it is possible to measure not only the surface portion of the subject but also the deep portion. Near-infrared rays are not radiation that is unexpected to the living body, such as X-rays (X-rays), and therefore, it is possible to strictly inspect a non-invasive subject.

  First, the OCT measurement principle will be briefly described. In general, light has a property as an electromagnetic wave, and thus has a property of interfering when light is superimposed. The interference performance of whether it is easy to interfere or difficult to interfere is also called coherence. In general OCT, near-infrared light having low coherence is used.

  1A and 1B are diagrams for explaining the principle of OCT measurement. Near-infrared light becomes a random signal as shown in the figure when time is taken on the horizontal axis and electric field is taken on the vertical axis. Each peak of the signal is called a wave train, and each wave train has an independent phase and amplitude. For this reason, when the same wave trains overlap, as shown in FIG. 1A, they interfere and strengthen each other. On the other hand, when there is a slight time delay, as shown in FIG. 1B, the wave trains cancel each other, and optical interference is not observed.

  OCT utilizes this property. FIG. 2 is a block diagram showing the overall configuration of a wavelength scanning optical tomography display system that realizes OCT. As shown in the figure, a near-infrared light source 10 that oscillates an optical signal in a certain frequency range is used as the wavelength scanning light source of this system. The wavelength of the light source 10 is, for example, 700 nm to 2500 nm, and corresponds to the wavelength of near infrared light that enters the living body. The output of the light source 10 is given to the optical fiber 11. In the middle portion of the optical fiber 11, a coupling portion 13 is provided that causes another optical fiber 12 to approach and interfere. One end of the optical fiber 12 is provided with a collimating lens 14 that converts an optical signal obtained from the light source 10 through the coupling unit 13 into parallel light, and a scanning mirror 15 for scanning the light.

  Examples of the scanning mirror 15 include a galvanometer mirror, a MEMS mirror, and a mirror arranged in a round shape. The scanning mirror 15 changes the reflection angle of parallel light by, for example, rotating within a certain range about an axis perpendicular to the paper surface. Then, by rotating the scanning mirror 15 and changing the incident position of the light, a cross-sectional image that is two-dimensional information of the object 30 can be obtained. In addition, by scanning (scanning) the object 30 in a direction perpendicular to the parallel light, three-dimensional information indicating the layer structure inside the object 30 can be acquired.

  The objective lens 16 is disposed at a position for receiving the reflected light, and focuses the light on the measurement site of the object 30 and scans (scans) it in the horizontal direction. Further, a reference mirror 18 is provided at the other end of the optical fiber 11 via a collimator lens 17 perpendicular to the optical axis. Here, the optical distance L1 from the coupling portion 13 to the reference mirror 18 and the optical distance L2 from the coupling portion 13 to the surface that is the measurement site of the object 30 are set equal. A photodetector 21 is connected to the other end of the optical fiber 12 via a lens 20. The reference mirror 18 interferes with the backscattered light returning from the object 30 and creates interference light. The photodetector 21 is composed of, for example, a light receiving element or a CCD (Charge Coupled Device) image sensor, and receives a beat signal by receiving reflected light from the reference mirror 18 and interference light reflected from the measurement site. Obtained as an electrical signal. Here, the optical fiber 11, the optical fiber 12, the coupling portion 13, the collimating lens 14, the scanning mirror 15, the objective lens 16, the collimating lens 17, the reference mirror 18, and the collimating lens 20 constitute an interference optical meter. .

  The output of the photodetector 21 is input to the signal processing unit 23 via the amplifier 22. The signal processing unit 25 obtains a tomographic image signal by performing a Fourier transform on the received light signal obtained from the interference optical meter. The output from the signal processing unit 23 is given to the image processing unit 24. The image processing unit 24 generates a two-dimensional or three-dimensional image of the object 30 based on the output from the signal processing unit 23. The display image generated in this way is displayed by the display unit 25.

  FIG. 3 shows an example of a tomographic image measured by OCT. When the surface of a human tooth is measured by OCT, for example, by OCT, as shown in the figure, the gingiva, enamel, dentin, and the boundary between enamel and dentin become faulty. The displayed image is displayed. That is, an image including enamel, dentin, pulp, gingiva, alveolar bone, blood vessels, nerves, and the like in the interior (deep part) of the tooth that is the object 30 is obtained by OCT measurement.

  FIG. 4 is a diagram illustrating a light irradiation method. The irradiation method shown in the figure is generally called a raster method. However, as shown in the figure, the irradiation light applied to the object 30 spreads in a fan shape and is applied to the object 30 when the scanning mirror 15 performs a rotational motion around a predetermined position. . That is, since the irradiation light irradiated to the target object 30 is not strictly parallel, a slight time lag occurs until the irradiation light reaches the center part and both end parts of the target object 30. For this reason, the target object 30 measured by OCT becomes an image including distortion. Similar time lag occurs in other irradiation methods such as the round method.

  FIG. 5 is a diagram illustrating the distortion of the object. In the OCT measurement, an image including distortion is obtained by a slight time lag until the irradiation light reaches the object 30 as shown in FIG. For this reason, when measuring the target object 30 like a tooth, the distortion and error contained in this image may become a problem.

  FIG. 6 is a diagram comparing the actual tooth image and the OCT image. The portion indicated by the arrow in the figure is the enamel layer of the tooth (the layer from the tooth surface to the boundary between the enamel and the dentin) and is the same portion of the same tooth. As shown in the figure, there is a difference between the actual image and the OCT image. Therefore, the reference grid used for correcting the difference will be described below.

  FIG. 7 is a diagram showing a schematic configuration of the reference grating 100 according to the present embodiment. The reference grid 100 according to the present embodiment is typically used when measuring a tooth shape by OCT. In order to treat dental caries, so-called decayed teeth, the restoration of the tooth or dental prosthesis, so-called inlay, is carried out by loading the cavity (carious hole) from which the caries have been removed. Here, the inlay refers to a lump of metal or porcelain that is formed so that the tooth is formed in a certain shape against a partial defect of the crown due to trauma or caries and conforms to the defective part. . In order to determine the shape and size of the restoration or prosthesis loaded in the cavity, it is necessary to measure the shape and size of the cavity. Therefore, by using the reference grating 100, distortion and error are corrected, and OCT measurement is performed with high accuracy.

  The reference lattice 100 is formed in a substantially cubic shape as shown in FIG. The reference grating 100 is formed in a size of 1 mm square, 3 mm square, 5 mm square, or the like, which is adapted to the size of the cavity.

In addition, since the shape and size of the tooth that is the object 30 and the shape and size of the cavity formed in the tooth are different, the reference lattice 100 can be formed in an arbitrary shape and size.
Further, the reference lattice 100 is not limited to a cube, and is arbitrary such as a rectangular parallelepiped, a triangular prism, a cylinder, or a cone.

  The reference lattice 100 is made of, for example, an acrylic resin or a polymethyl methacrylate resin.

The material of the reference grating 100 is arbitrary as long as the reference grating 100 is reflected by OCT measurement through light (near infrared rays). In addition, the material of the reference grating 100 may be a material having a slightly large scattering coefficient having transparency.
This is because regular reflection can be suppressed by increasing the scattering coefficient.

  Moreover, the reference | standard grating | lattice 100 is provided with the some grid line 110, as shown in FIG.

  The grid lines 110 are formed on the reference grid 100 at predetermined intervals. As shown in the figure, each grid line 110 is formed on the reference grid 100 so as to form a grid, for example. The grid lines 110 are formed, for example, at intervals of 100 μm, and are formed so that the grid lines 110 and the outer peripheral portion of the reference lattice 100 are vertical.

  Note that the intervals between the grid lines 110 do not have to be equal, and are arbitrary as long as the actual dimensions can be measured. This is because the measured value of the interval between the grid lines 110 measured by OCT and the interval between the grid lines 110 are measured. This is because the distortion and error of the OCT image obtained by the measurement are corrected by comparing with the actual size value.

  Further, the number, thickness, groove depth, arrangement position, and the like of the grid lines 110 are arbitrary. For example, the grid lines 110 having different levels can be arranged on the reference lattice 100 to such an extent that it effectively works for image correction. This is because attenuation and artifacts can be dealt with.

  The actual dimensions of the intervals, thicknesses, shapes, and the like of the grid lines 110 are measured in advance before the OCT measurement, and the distortion of the OCT image is corrected based on the actual dimensions.

  8A and 8B are sectional views taken along line AA shown in FIG. As shown in FIG. 8A, the grid line 110 is formed so as to penetrate the inside of the reference lattice 100. Further, the grid lines 110 may be formed only on the outer peripheral portion (surface) of the reference lattice 100 as shown in FIG. 8B. The OCT image is corrected based on the difference between the grid line 110 displayed in the OCT image and the actual grid line 110. Therefore, any grid line 110 that can correct the OCT image is optional.

  The method for forming the grid lines 110 on the reference grid 100 is arbitrary. For example, the grid lines 110 can be formed by irradiating the reference grating 100 with a predetermined laser beam. Further, by joining a plurality of solids of a predetermined size, it is possible to form the reference lattice 100 in which the boundary where the solids are joined becomes the grid line 110.

  Next, a method of using the reference grid 100 will be described with reference to the drawings.

  FIG. 9 is a diagram for explaining the installation position of the reference grid 100. The reference grid 100 is typically used when measuring the shape of a tooth by OCT. To determine the shape and size of the caries hole formed by the caries and the restoration or prosthesis that is loaded into the cavity where the caries have been removed to treat the caries, the cavity It is necessary to measure the shape and size of the (pit). Therefore, the reference lattice 100 is installed so as to be buried in the cavity formed in the tooth as shown in FIG.

  The reference lattice 100 is fixed to the cavity of the tooth through an adhesive member that transmits light (near infrared rays), for example. An adhesive member is applied or adhered to the tooth cavity or the reference lattice 100, and the reference lattice 100 is adhered to the cavity.

  In addition, the reference | standard grating | lattice 100 should just be stationary in the case of OCT measurement. For this reason, the member is arbitrary as long as the material has adhesiveness enough to temporarily fix the reference lattice 100 to the cavity and transmits light. The amount of the member for fixing the reference lattice 100 to the cavity is arbitrary, and the reference lattice 100 may be fixed to the cavity without using a member.

  Also, the reference grid 100 having any shape and size can be installed in the cavity depending on the shape and size of the cavity. For example, in the case of a vertically deep cavity, a vertically long reference grid 100 that matches the shape of the cavity can also be installed.

  FIG. 10 is a diagram for explaining how to use the reference grating 100. The reference grating 100 is fixed to the cavity of the tooth. Typically, as shown in the figure, OCT light is irradiated to the tooth and the reference grating 100 from the direction in which the cavity is open. At the time of OCT measurement, out of the light that spreads in a fan shape around the predetermined position and is irradiated to the teeth, the center light that is positioned at the center of the irradiation region and the center grid line that is the center of the reference grating 100 are It is preferable to irradiate so that it may correspond substantially. This is for facilitating correction of an image to be described later.

  Even when the central light and the central grid line do not match, the OCT image can be corrected. For this reason, the setting position of the reference | standard grating | lattice 100 and the irradiation direction of light are arbitrary.

  FIG. 11 is an example of an OCT image including the reference grid 100. By performing the OCT measurement, as shown in the figure, an OCT image in which the grid lines 110 of the reference lattice 100 are displayed is acquired. From the OCT image, the inner shape of the cavity, the angle of the slope, the depth, and the like are measured as information on the cavity.

  However, as described above, since distortion or the like exists in the OCT image, the reference lattice 100 and the grid line 110 on the OCT image are distorted, and the distance is extended in the depth direction. Therefore, based on the actual dimensions of the grid 110, correction is performed so that the reference grid 100 and the grid lines 110 on the OCT image coincide with the actual dimensions. By correcting the distortion, the inner shape of the cavity can be measured more accurately. A typical image correction method is shown below.

  FIG. 12 is an example of the corrected OCT image. The actual distance between the grid lines 110 included in the reference grid 100 measured by OCT is measured in advance. For this reason, the correction ratio (correction value) is obtained by comparing the actual size value between the grid lines 110 and the measured value between the grid lines 110. Then, as shown in the figure, the distortion of the grid line 110 and the like are corrected, whereby more accurate cavity information of the cavity inner shape, slope angle, and depth is acquired.

  In the OCT image, barrel distortion is relatively noticeable. Here, barrel distortion refers to an aberration in which a subject is bent like a barrel when a straight portion of the subject is distorted and bent. In general, the most significant geometric distortions are radial distortion and tangential distortion. For this reason, it is considered that radial distortion and tangential distortion are generated in a composite manner on the OCT image.

Radial distortion causes a shift in the position from the ideal lens to the inside or outside of the image. The inward displacement (negative displacement) is barrel distortion, and the outward displacement (positive displacement) is pincushion. Called distortion. The radial distortion is expressed by the following series.
σ _r = k ₁ r ³ + k ₂ r ⁵ + k ₂ r ⁷ +...
Where r: distance from the optical axis point, k ₁ , k ₂ , k ₃ ...: Distortion coefficient.

Further, an expression in which all distortions are combined is expressed as follows. In this equation, the most prominent effect is a radial distortion term whose coefficient is k _{1. In} many cases, only this factor is considered.
σ _u = s ₁ (u ² + v ² ) + 3p ₁ u ² + p ₁ v ² + 2p ₂ uv + k ₁ u (u ² + v ² ),
σ _v = s ₂ (u ² + v ² ) + 2p ₁ uv + p ₁ u ² + 3p ₂ v ² + k ₁ v (u ² + v ² ).

If the coordinates of the point on the image before correction having distortion are (x _d , y _d ), and the coordinates of the corresponding point on the image after distortion correction are (x _u , _yu ), the following formula is established. To do.
x _u = (1 + K _1r ² + K _2r ⁴ ) x _d + (2P ₁ xy + P ₂ (r ₂ + 2x ² )),
^{_{y u = (1 + K 1r}} 2 + K 2r 4) y d + (P 1 (r 2 + 2y 2) + 2P 2 xy),
Where x = x _d -C _x , y = y _d -C _y , r ² = x ² + y ² , C _x and C _y : optical center on the image, K _i : barrel distortion variable, P _i : circle Circumferential distortion variable.

  From the above equation, a correction value (correction coordinate) is obtained from the measurement value (measurement coordinate) and actual size value (actual coordinate) of the grid line 110. For this reason, a more accurate OCT image can be acquired by correcting the OCT image on which the reference grid 100 is displayed by measuring the reference grid 100 whose actual dimensions are measured in advance by OCT.

  In addition, it can correct | amend by well-known methods, such as barrel distortion, pincushion distortion, tangential distortion, radial distortion, or the distortion which combined these. In addition, the image can be corrected by any method. In addition, the image can be corrected even when light that has passed through the reference grating 100 or the grid lines 110 is irregularly reflected.

  Further, it is possible to irradiate the teeth and the reference lattice 100 with irradiation light at an arbitrary angle. In OCT, imaging is performed by amplifying and detecting scattered light emitted from the inside of a tooth due to interference. For this reason, in the measured raw data, the reflected light has a luminance that is too strong with respect to the surrounding signal values, which may result in an artifact. In other words, it is necessary to devise a way to prevent regular reflection at the boundary surface when the reference grating 100 is irradiated with light. In addition, it is necessary to adjust the refractive index by performing anti-reflective processing on the material itself and processing the interface. However, when correcting an image, it is considered that incidence at 90 degrees enables higher accuracy, but the accuracy can be sufficiently effectively improved even at incidence other than 90 degrees with respect to an image before correction.

Thereby, by using the reference lattice 100, an image including distortion acquired by performing the OCT measurement can be corrected. Then, the shape of the cavity of the tooth is measured from the undistorted tooth image, and a restoration or prosthesis for loading into the shape of the cavity can be created.
In addition, if the image distortion cannot be completely corrected even if the reference grating 100 is used, it becomes clear that it is necessary to select another lens having a different focus for correcting the trajectory of light from the OCT. A lens most suitable for measurement can be selected.

  Next, an optical coherence tomographic image diagnosis apparatus including the reference grating 100 will be described. FIG. 13 is a diagram showing a schematic configuration of the optical coherence tomographic image diagnostic apparatus 200. As shown in FIG. As shown in the figure, the optical coherence tomographic image diagnostic apparatus 200 includes a measurement unit 210, a storage unit 220, a correction unit 230, a display unit 240, and the like. Hereinafter, each component of the optical coherence tomography diagnostic apparatus 200 will be described. In addition, although the function of each part is mutually linked | related, the acceptance / rejection of each part can be changed suitably according to a use.

  As shown in FIG. 2, the measurement unit 210 includes a light source 10, an optical fiber 11, an optical fiber 12, a coupling unit 13, a collimating lens 14, a scanning mirror 15, an objective lens 16, a collimating lens 17, a reference mirror 18, and a collimating. The lens 20 and the like. The measurement unit 210 measures the object 30 (here, a human tooth) based on the basic principle of OCT described above. And the measurement part 210 outputs an OCT image based on the measured value measured.

  FIG. 14 is a diagram illustrating a measurement unit 210 including the reference grating 100. As shown in the figure, the measurement unit 210 includes, for example, a reference lattice 100 at the tip for irradiating light to teeth.

  Note that the measurement unit 210 may be one in which the reference lattice 100 is connected to the tip of a measurement probe provided in a general OCT capable of measuring morphological information of a living tissue. For this reason, the measurement unit 210 uses, for example, a known measurement method of Fourier domain OCT (FD-OCT) such as spectral domain OCT (SD-OCT) or wavelength scanning OCT (SS-OCT), and other methods. Also in OCT, living tissues such as teeth can be measured.

  The measurement unit 210 can also include the reference grating 100 at an arbitrary position. In addition, the reference grating 100 can be detached from the measurement unit 210.

  The storage unit 220 includes, for example, a RAM (Random Access Memory), a hard disk, and the like, and stores the actual size value between the grid lines 110 of the reference grid 100 provided in the measurement unit 210. The storage unit 220 can also store arbitrary information such as a measurement value measured by the measurement unit 210 and an OCT image corrected by the correction unit 230.

  The correcting unit 230 corrects the OCT image based on the measured value of the interval between the grid lines 110 measured by the measuring unit 210 and the actual size value of the interval between the grid lines 110 stored in the storage unit 220. The correction unit 230 compares the measurement value between the grid lines 110 and the actual size value, corrects the measurement value by an arbitrary method, and corrects the OCT image.

  The display unit 240 is composed of a liquid crystal display, for example, and displays the OCT image corrected by the correction unit 230. The display unit 240 can also display an arbitrary image such as an OCT image before and after correction.

  Next, image correction processing executed by the optical coherence tomographic image diagnosis apparatus 200 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, the storage unit 220 stores the actual size value of the reference grid 100 included in the measurement unit 210 and the actual size value between the grid lines 110 (step S101). The actual size value between the reference grid 100 and the grid line 110 is measured in advance by a predetermined apparatus and method, and the measured value is stored as the actual size value.

  The storage unit 220 can also store actual size values between the grid lines 110 of the plurality of reference grids 100. For example, when the reference grid 100 included in the measurement unit 210 is detachable, the storage unit 220 can also store the actual size values between the grid lines 110 corresponding to all the reference grids 100 attached to the measurement unit 210.

  Next, the measurement unit 210 measures a tooth that is an object (step S102). As shown in FIG. 14, a measurement unit 210 including a reference lattice 100 is disposed near a tooth for which measurement is desired. When the measurement unit 210 is disposed at a predetermined position, and when an instruction input indicating the start of measurement is made by an operator who operates the optical coherence tomographic image diagnostic apparatus 200, the tooth shape and the tooth are formed. The shape of the cavity is measured.

  The measurement unit 210 can measure the shape of any tooth and the shape of any cavity formed in the tooth.

  Next, the correction unit 230 compares the measurement value between the grid lines 110 measured by the measurement unit 210 with the actual size value between the grid lines 110 stored in the storage unit 220 (step S103). An image showing the grid line 110 based on the measurement value measured by the measurement unit 210 is an image including distortion, as shown in FIG. For this reason, the correction | amendment part 230 correct | amends so that the grid line 110 based on a measured value may correspond with the grid line 110 based on an actual size value.

  Next, the correcting unit 230 calculates a correction value for making the measured value between the grid lines 110 coincide with the actual size value between the grid lines 110 based on the difference between the measured value and the actual size value (step S104). Then, the correction unit 230 outputs an OCT image based on the correction value.

  Note that the correction unit 230 can calculate the correction value by any method that matches the measured value with the actual size value.

  Next, the display unit 240 displays an OCT image based on the correction value output from the correction unit 230 (step S105). As shown in FIG. 12, an OCT image on which the reference grid 100 with the corrected grid line 110 is displayed is displayed on a monitor or the like.

  As described above, according to the present invention, optical coherence tomographic image diagnosis can be performed with high accuracy. Further, since the shape of the cavity of the tooth can be measured based on the image of the tooth without distortion, a restoration or prosthesis for loading into the shape of the cavity can be created.

  In addition, this invention is not limited to said embodiment, A various deformation | transformation and application are possible.

  FIG. 16 is a diagram illustrating a modification of the reference lattice 100. The reference grid 100 may have a shape and a size that cover teeth as shown in FIG. The reference grid 100 is typically used when creating a so-called crown. Here, when the majority of the tooth is missing due to caries or the like, the crown is formed by cutting all surfaces of the tooth crown and coating it with metal or a crown color material.・ Restore aesthetics. By covering the entire tooth with the reference lattice 100, an OCT image showing the entire tooth can be corrected based on the reference lattice 100. A restoration or prosthesis to be loaded on the tooth can also be created.

  FIG. 17 is a view showing a modification of the cross section taken along line AA of FIG. The grid lines 110 may be formed only inside the reference grid 100 as shown in FIG. If the distortion included in the OCT image can be corrected by comparing the measured dimension between the grid lines 110 and the actual dimension between the grid lines 110, the arrangement of the grid lines 110 is arbitrary.

  The optical coherence tomographic image diagnosis apparatus 200 can also include a creation unit that creates a restoration or prosthesis for loading into the cavity of a tooth. The creation unit creates a restoration or prosthesis corresponding to the cavity shape based on the cavity shape on the corrected OCT image. The creation unit can create a restoration or prosthesis having an arbitrary shape and size.

  Note that when creating a restoration or prosthesis, the creation unit reduces the size of the restoration or prosthesis to a small size only in the bonding area for bonding the tooth cavity and the restoration or prosthesis. It can also be created. For example, when the cement line is 5 μm to 50 μm, the creation unit creates a restoration or prosthesis in which a region to which the adhesive (cement) of the restoration or prosthesis is applied is reduced by 5 μm to 50 μm. You can also.

  As described above, according to the present invention, it is possible to provide a reference lattice suitable for performing optical coherence tomographic image diagnosis with high accuracy, a method of using the reference lattice, and an optical coherence tomographic image diagnosis apparatus including the reference lattice. Can do.

DESCRIPTION OF SYMBOLS 10 Light source 11, 12 Optical fiber 13 Coupling part 14, 17, 20 Collimating lens 15 Scanning mirror 16 Objective lens 18 Reference mirror 21 Photo detector 22 Amplifier 23 Signal processing part 24 Image processing part 25 Display part 30 Target object 100 Reference grating 110 Grid line 200 Optical coherence tomography diagnostic apparatus 210 Measuring unit 220 Storage unit 230 Correction unit 240 Display unit

Claims (7)

A reference grid used for diagnosis of optical coherence tomographic images,
It consists of a member that transmits light,
The member comprises a plurality of grid lines,
The reference grating is measured together with the object displayed in the optical coherence tomographic image,
The plurality of grid lines are displayed in the optical coherence tomographic image.
Reference grid characterized by that. An interval between the grid lines is predetermined at a predetermined distance,
The reference grid according to claim 1. The grid lines are arranged in a grid pattern,
The reference grid according to claim 2. A method of using a reference grid according to claim 1,
Fixing the reference grating on the object,
Irradiate the fixed reference grating and the object with low interference light, and measure the reference grating and the object based on the reflected light obtained by reflecting the low interference light by the reference grating and the object. ,
Identifying an error included in the measured dimension of the measured object based on the difference between the measured dimension between the grid lines of the measured reference grid and the actual dimension between the grid lines;
A method of using a reference grid characterized in that. Correcting the identified error and displaying an optical coherence tomographic image based on the measured dimensions of the corrected object;
The use method of the reference | standard grating | lattice of Claim 4 characterized by the above-mentioned. An optical coherence tomography diagnostic apparatus comprising the reference grating according to claim 1,
Irradiated with low coherent light to the reference grating and the object, and the reference grid the low interference light by and the object based on the reflected light which is reflected, measuring unit for measuring the reference grating and the object ,
A storage unit for storing actual dimensions between grid lines included in the reference grid;
A correction unit that corrects an error included in the measured dimension of the measured object based on a difference between a measured dimension between grid lines included in the measured reference grid and an actual dimension between the grid lines;
And a display unit for displaying an optical interference tomographic image based on the measurement size of the corrected object,
An optical coherence tomography diagnostic apparatus comprising a reference grating characterized by the above. The measurement unit includes the reference grating at a tip for irradiating the low interference light.
  The optical coherence tomography diagnostic apparatus according to claim 6.