System for improving visibility of dental panoramic x-ray image for assisting in diagnosis of osteoporosis, method for improving visibility, program for improving visibility, and storage medium for program for improving visibility

Abstract

Provided is a system for improving the visibility of a dental panoramic X-ray image in order to assist a dentist in the diagnosis of osteoporosis by visual image recognition. This system for improving the visibility of a dental panoramic X-ray image for assisting in the diagnosis of osteoporosis includes: an image display unit for displaying a captured or edited dental panoramic X-ray image; a mandible portion visibility improvement unit for improving the visibility of a mandible portion of the image displayed on the image display unit; and a control unit for the panoramic X-ray image visibility improvement system, for controlling the image display unit and the mandible portion visibility improvement unit.

Description

Visibility improvement system, visibility improvement method, visibility improvement program, and visibility improvement program storage medium for dental panoramic X-ray images for osteoporosis diagnosis support

[0001] The present invention relates to a system, a method, a program, and a storage medium for a visibility improvement program for improving visibility of dental panoramic X-ray images for supporting the diagnosis of osteoporosis, for example, and more particularly to a system, a method, a program, and a storage medium for a visibility improvement program for improving visibility of dental panoramic X-ray images for supporting the diagnosis of osteoporosis, for improving the visibility of dental panoramic X-ray images for supporting the diagnosis of osteoporosis.

[0002] In the field of dentistry, panoramic radiographs of the teeth are widely used to assist in diagnosing the name of the disease, the extent of the lesion, and in selecting treatment methods. At the same time, images of the mandibular cortical bone are also taken as images of the surrounding area of ​​the teeth, and the use of these images to assist in the diagnosis of osteoporosis is becoming increasingly widespread.

[0003] For example, the Japanese Society of Dental Radiology published the "Clinical Guidelines for Osteoporosis Screening Using Panoramic X-ray Images" in 2021.

[0004] Furthermore, Patent Document 1 discloses the technical concept of an osteoporosis diagnostic support device that semi-automatically determines whether the inner surface of cortical bone is smooth or rough using panoramic X-ray images.

[0005] Patent Document 2 discloses the technical concept of an osteoporosis diagnostic support device that has a means for determining the thickness of the cortical bone from a panoramic X-ray photograph, comparing the thickness of the cortical bone with data stored in a database, and making a determination as to whether the patient has osteoporosis.

[0006] Patent Document 3 discloses a technical concept for measuring the thickness of cortical bone with higher accuracy and assisting in the diagnosis of osteoporosis.

[0007] However, such osteoporosis diagnostic support technology using automatic calculation methods cannot be said to support dentists in making diagnoses by visually inspecting images, and there is a problem in that it is difficult to gain the trust of both dentists and patients.

[0008] If osteoporosis diagnosis using dental panoramic X-ray images becomes covered by insurance in the future, screening of mandibular cortical bone by dentists will become more widespread, and the poor visibility of mandibular cortical bone is expected to become a problem.

[0009] Japanese Patent Application Laid-Open No. 2004-209089 International Publication No. 2006 / 043523 Japanese Patent Application Laid-Open No. 2012-143387

[0010] Therefore, an object of the present invention is to provide a system that improves the visibility of dental panoramic X-ray images in order to assist dentists in diagnosing osteoporosis by visually examining the images.

[0011] In order to solve the above problems, a first aspect of the present invention is a system for improving visibility of dental panoramic X-ray images for assisting in the diagnosis of osteoporosis, characterized by having an image display unit that displays a captured or edited dental panoramic X-ray image, a mandible portion visibility improvement unit that improves the visibility of the mandible portion of the image displayed on the image display unit, and a panoramic X-ray image visibility improvement system control unit that controls the image display unit and the mandible portion visibility improvement unit.

[0012] An edited image refers to an image that has been corrected, adjusted, etc. Also, the "system for improving visibility of dental panoramic X-ray images to support osteoporosis diagnosis" may be abbreviated as "system for improving visibility of dental panoramic X-ray images," and the "mandibular portion visibility improvement unit" may be abbreviated as "visibility improvement unit."

[0013] In the present invention, the mandible portion of a dental panoramic X-ray image is the most appropriate portion for diagnosing osteoporosis, but other portions may also be used depending on the situation.

[0014] The mandible, which is depicted simultaneously in panoramic X-ray images taken primarily for the purpose of observing teeth, has variations in image brightness or contrast. Therefore, normalizing and standardizing the image to make it easier to compare with other images improves visibility, enabling dentists to accurately diagnose the presence and severity of osteoporosis through visual observation.

[0015] Next, as a second aspect of the present invention, in the system for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis of the first aspect, the mandible portion visibility improvement unit may be characterized in that it normalizes the shading of the image.

[0016] Here, normalization of image shading means making images of different shadings uniform to the same level of shading, making it easier and more accurate for dentists to make a diagnosis through visual observation, and is sometimes referred to as standardization.

[0017] For this purpose, Gaussian correction is preferably used, although other methods may also be used.

[0018] Next, as a third aspect of the present invention, in the system for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis of the first aspect, the mandible portion visibility improvement unit may be characterized by adjusting the shading of the image.

[0019] Image shading adjustment refers to converting the contrast of an image with little difference in shading to make it easier to see. In particular, in cases where emphasizing the contrast near the middle of shading (halftones) is effective in improving visibility, it is preferable to use a sigmoid function to adjust the shading near the middle, but this method is not limited to this.

[0020] As explained above, the improvement of visibility can also be expressed as normalization or standardization of shading and improvement of contrast based on the mandible or mandibular cortical bone.

[0021] Dental panoramic X-rays have a wide variety of shades, and dentists are required to be able to interpret images of the mandibular cortical bone in a variety of shades, such as crushed black, medium-tone, and blown-out white areas.

[0022] On the other hand, according to the present invention, the shades of the mandibular cortical bone are normalized (standardized) to intermediate tones, and further the shades of the intermediate tones are adjusted (contrast is improved). This means that the mandibular cortical bone is depicted in intermediate tones regardless of the imaging system used to capture the image. Therefore, it is only necessary to be able to interpret the intermediate tones of the mandibular cortical bone, and it is expected that stable visual evaluation will be possible regardless of variations in shade.

[0023] Furthermore, in order to solve the above-mentioned problems, a fourth aspect of the present invention is a method for improving visibility of dental panoramic X-ray images for assisting in the diagnosis of osteoporosis, the system for improving visibility of dental panoramic X-ray images comprising: an image display unit that displays a captured or edited dental panoramic X-ray image; a mandible portion visibility improvement unit that improves the visibility of the mandible portion of the image displayed on the image display unit; and a panoramic X-ray image visibility improvement system control unit that controls the image display unit and the mandible portion visibility improvement unit, the system comprising: a step in which the mandible portion visibility improvement unit determines a maximum pixel value of the mandible cortical bone from a prepared dental panoramic X-ray image; a step in which the mandible portion visibility improvement unit normalizes the maximum pixel value of the mandible cortical bone so that it becomes a halftone; a step in which the mandible portion visibility improvement unit adjusts the shade of the normalized halftone (enhances the contrast); and a step in which the system control unit displays the image on the image display unit after applying the normalization and shade adjustment to improve visibility.

[0024] Here, the method of determining the maximum pixel value of the mandibular cortical bone includes not only a method in which the mandibular portion visibility improvement unit automatically determines the value, but also a method in which the mandibular portion visibility improvement unit allows the user to manually specify the pixel value related to the mandibular cortical bone.

[0025] Specific approaches include the following: - Prepare a program to calculate the maximum value within a region of interest, and when the user specifies the region of interest, the maximum value is found. - Implement a function similar to the eyedropper tool in Windows paint software, and read out the pixel value of the pixel that the user specifies as the maximum pixel value.

[0026] That is, whatever the method, by finding the maximum pixel value of the image of the mandibular cortical bone portion, it becomes possible to correct the shading based on the pixel value relating to the mandibular cortical bone.

[0027] The technical concepts of the above steps may be applied to AI technologies such as deep learning using neural networks to generate high-quality trained models and obtain optimal visibility for unknown images.

[0028] Next, as a fifth aspect of the present invention, in the method for improving visibility of dental panoramic X-ray images for assisting in the diagnosis of osteoporosis according to the fourth aspect, the step of determining the maximum pixel value of the mandibular cortical bone may include a step of calculating pixel values ​​(shading) for a predetermined region of interest including the mandibular cortical bone of the image in which the mandibular bone partial visibility improvement unit is provided.

[0029] In this embodiment, specifically, pixel values ​​related to the mandibular cortical bone are calculated from a predetermined region of interest including the mandibular cortical bone, and the maximum pixel value is determined, so that the shading can be corrected based on the maximum pixel value. This step can be performed automatically.

[0030] According to the fourth or fifth aspect, by following these steps, it is possible to improve the visibility of the mandibular cortical bone in a dental panoramic X-ray image.

[0031] A sixth aspect of the present invention is a program for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis, which program executes the method of the fourth or fifth aspect of the present invention.

[0032] A seventh aspect of the present invention is a program storage medium for storing a program for improving the visibility of dental panoramic X-ray images to assist in the diagnosis of osteoporosis, which stores the program of the sixth aspect of the present invention in a manner that is executable by the control unit of the panoramic X-ray image visibility improvement system.

[0033] The mandibular bone portion visibility improvement section of the present invention allows the intensity of shading to be adjusted, thereby obtaining suitable correction results and enabling dentists to use it as a tool for visual screening.

[0034] 1 is a functional configuration diagram of a system for improving visibility of dental panoramic X-rays (hereinafter sometimes abbreviated as the visibility improvement system) according to one embodiment of the present invention. A hardware configuration diagram of a system for improving visibility according to one embodiment of the present invention. A flowchart of the operation of a system for improving visibility according to one embodiment of the present invention. An example of an image prepared by a system for improving visibility according to one embodiment of the present invention. A correction status of an image by a system for improving visibility according to one embodiment of the present invention. A correction status of an image by a system for improving visibility according to one embodiment of the present invention. A correction result of an image by a system for improving visibility according to one embodiment of the present invention. A graph of a pseudo-sigmoid function used in a system for improving visibility according to one embodiment of the present invention. A shading adjustment status of a system for improving visibility according to one embodiment of the present invention, a shading adjustment status of a system for improving visibility according to one embodiment of the present invention, a shading adjustment status of a system for improving visibility according to one embodiment of the present invention, and a result of the shading adjustment by a system for improving visibility according to one embodiment of the present invention.

[0035] Hereinafter, a system for improving visibility of dental panoramic radiographs for supporting osteoporosis diagnosis according to one embodiment of the present invention will be described with reference to the drawings. Note that the scope necessary for the explanation to achieve the object of the present invention will be schematically shown below, and the scope necessary for explaining the relevant parts of the present invention will be mainly explained, and the parts that are omitted from the explanation will be based on known techniques.

[0036] <Configuration of a System for Improving Visibility of a Panoramic X-ray Photograph> FIG. 1 is a functional configuration diagram of a system 1 for improving visibility of a dental panoramic X-ray photograph for supporting the diagnosis of osteoporosis according to one embodiment of the present invention.

[0037] The image display unit 10 displays a captured or edited dental panoramic X-ray image, and is a display such as an LCD that is widely used in dentistry.

[0038] The mandible portion visibility improving unit 20 has a function of improving the visibility of the mandible portion of the image displayed on the image display unit, and is configured by an application program.

[0039] The panoramic X-ray image visibility improving system control unit 30 (hereinafter sometimes abbreviated as the system control unit 30 ) is a unit that controls the image display unit 10 and the mandible portion visibility improving unit 20 .

[0040] In addition, the dental imaging system may have functional parts such as an image capturing unit 40 for capturing dental panoramic images and an image storage unit 50 for storing captured images.

[0041] FIG. 2 is a hardware configuration diagram of a system 1 for improving the visibility of dental panoramic X-ray photographs to support the diagnosis of osteoporosis according to one embodiment of the present invention, which can be realized by a PC or server comprising a central processing unit 101 including an operation unit that performs arithmetic and logical operations and a control unit that controls the operation of other components, a storage device 102 for saving and storing data and programs, an input device 103 for providing data, information, instructions, etc. to a device such as a computer, and an output device 104 that receives data from a computer or a running program and physically presents it externally in a form that can be recognized by humans.

[0042] Regarding the hardware configuration, the components may be installed in a distributed manner, such as in cloud computing, and in that case the functional parts described above may be integrated or separated.

[0043] <Operation of the System for Improving Visibility of Panoramic X-ray Photographs> The operation of the system 1 for improving visibility of dental panoramic X-ray photographs for supporting osteoporosis diagnosis, configured as described above, will now be described. Figure 3 is a flowchart of the operation of the system 1 for improving visibility of dental panoramic X-ray photographs according to one embodiment of the present invention.

[0044] First, the system control unit 30 prepares a dental panoramic X-ray image (step S-11). The prepared image may be any image captured by the image capturing unit 40 included in the system, an image stored in the image storage unit 50 that stores captured images, or an image captured by an external image capturing device not included in the system.

[0045] Next, the mandible portion visibility improving unit 20 sets a region of interest in the mandible portion of the prepared image (step S-12).

[0046] FIG. 4 shows examples of images prepared by the system 1 for improving visibility of dental panoramic X-ray photographs according to one embodiment of the present invention, where FIG. 4(a) shows an image that is close to black, FIG. 4(b) shows an image that is gray, and FIG. 4(c) shows an image that is close to white. The top row shows the original image, and the bottom row shows an enlarged region of interest (small rectangular part) of the mandible part of the original image in the top row.

[0047] Here, the region of interest is set so that the pixel value on the mandibular cortical bone is the maximum (the whitest pixel), i.e., the region is set so that it includes the mandibular cortical bone but does not include any parts with higher pixel values ​​than the mandibular cortical bone (such as the metal part of a dental prosthesis).

[0048] If the region of interest is set as shown in Figure 4, it will not include dental prostheses or marks written on the image (e.g., the letter R), and therefore will not include areas with pixel values ​​higher than the mandibular cortical bone, and the maximum pixel value will be indicated by the pixels in the mandibular cortical bone area.

[0049] The object of the present invention is to improve the visibility of the mandibular cortical bone, and it is desirable that the standard for the shading correction, which is the means for achieving this, is the value of pixels associated with the mandibular cortical bone. While the easiest process is to find the maximum pixel value of the region of interest, it is also acceptable to find a value representative of the mandibular cortical bone (e.g., an average value) other than the maximum pixel value, if there is a means for finding that.

[0050] Subsequently, the mandible portion visibility improving unit 20 applies gamma correction to the region of interest of the prepared image for normalization (step S-13).

[0051] Specifically, a parameter γ is calculated so that the maximum pixel value is α, and gamma correction is applied to the region of interest.

[0052] Gamma correction generally involves selecting a suitable parameter γ in the following equation 1 to correct the intermediate range between light and dark on an image.

[0053]

[0054] The gamma correction in the present invention is performed so that the maximum value of the region of interest of the mandibular cortical bone becomes α. For example, if the maximum value of the image (I_max) is 255, the maximum value of the region of interest of the mandibular cortical bone is 220, and α = 127.5, the gamma value for converting the maximum value of the region of interest of the mandibular cortical bone to α can be calculated using the following Equation 2.

[0055] When actually calculating by applying the gamma value, the result is as shown in Equation 3 below.

[0056] This becomes:

[0057] The gamma correction process itself is the same for both general gamma correction and the present invention, but the purpose of the present invention is to normalize the maximum value of the region of interest of the mandibular cortical bone rather than correcting halftones.

[0058] Figure 5 shows the gamma correction status of an image close to black using the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention, Figure 6 shows the gamma correction status of an image close to gray using the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention, Figure 7 shows the gamma correction status of an image close to white using the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention, and Figure 8 is a drawing-substitute photograph showing the gamma correction result of an image using the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention.

[0059] According to this, the effect of gamma correction is that when gamma correction is performed so that the maximum pixel value of the region of interest is 128, the visibility of the mandibular cortical bone improves, particularly in images that are close to black and images that are close to white.

[0060] In other words, the black blockage is eliminated in black images, and the white blockage is eliminated in white images. However, there is not much difference in gray images. This is thought to be because the difference in density between the mandibular cortical bone and the surrounding area is originally small, making the image unclear overall.

[0061] Subsequently, the mandibular cortical bone part visibility improving unit 20 performs shading adjustment using a sigmoid function on the image after gamma correction (step S-14).

[0062] The reason for adjusting the shading using a sigmoid function is that it is thought that adjusting the shading near the middle using a sigmoid function is effective, especially for mid-tone (gray) images, where the difference in shading between the mandibular cortical bone and the background is small.

[0063] Here, as the sigmoid function, it is preferable to use a pseudo-sigmoid function expressed by the following formula 4, whose range is [0, 1].

[0064]

[0065] FIG. 9 is a graph of a pseudo-sigmoid function used in the system 1 for improving visibility of dental panoramic radiographs according to an embodiment of the present invention, and shows that the shape of the graph changes depending on the value of the parameter t.

[0066] The pseudosigmoid function is sometimes called an extended pseudosigmoid function.

[0067] Figure 10 shows the state of shading adjustment using a sigmoid function on an image that is close to black in the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention. Figure 11 shows the state of shading adjustment using a sigmoid function on an image that is gray in the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention. Figure 12 shows the state of shading adjustment using a sigmoid function on an image that is close to white in the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention. Figure 13 shows the results of shading adjustment using a sigmoid function on an image in the system 1 for improving visibility in dental panoramic X-ray photographs according to one embodiment of the present invention, where Figure 13(a) shows an image that is close to black, Figure 13(b) shows an image that is gray, and Figure 13(c) shows an image that is close to white. All of these are photographs used as substitutes for drawings.

[0068] This shows that the effect of shading adjustment using a sigmoid function with an appropriately selected parameter t is particularly great for gray images.

[0069] Thereafter, the system control unit 30 performs correction and adjustment to display the image with improved visibility on the image display unit 10 (step S-15).

[0070] As a result of such correction and adjustment, as shown in the lower part of Figure 13, the original image, whether it is close to black, gray, or white, is displayed with approximately the same brightness and shading, making it easy for dentists to visually observe it accurately.

[0071] The present invention is a system for improving the visibility of dental panoramic X-rays to assist in the diagnosis of osteoporosis, and helps dentists easily diagnose the increasing number of osteoporosis patients as society ages. The system has great industrial applicability.

[0072] REFERENCE SIGNS LIST 1 Dental panoramic X-ray image visibility improvement system 10 Image display unit 20 Mandibular bone portion visibility improvement unit 30 Panoramic X-ray image visibility improvement system control unit 40 Image capturing unit 50 Image storage unit

Claims

1. A system for improving visibility of dental panoramic X-ray images to assist in the diagnosis of osteoporosis, comprising: an image display unit that displays a captured or edited dental panoramic X-ray image; a mandible portion visibility improvement unit that improves the visibility of the mandible portion of the image displayed on the image display unit; and a panoramic X-ray image visibility improvement system control unit that controls the image display unit and the mandible portion visibility improvement unit.

2. A system for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis according to claim 1, wherein the mandibular bone portion visibility improving unit normalizes the shading of the image.

3. A system for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis according to claim 1, wherein the mandibular portion visibility improving unit adjusts the shading of the image.

4. A system for improving the visibility of dental panoramic X-ray images, comprising an image display unit that displays a captured or edited dental panoramic X-ray image, a mandible portion visibility improvement unit that improves the visibility of the mandible portion of the image displayed on the image display unit, and a panoramic X-ray image visibility improvement system control unit that controls the image display unit and the mandible portion visibility improvement unit, wherein the mandible portion visibility improvement unit determines the maximum pixel value of the mandible cortical bone from a prepared dental panoramic X-ray image, the mandible portion visibility improvement unit normalizes the pixel values ​​of the region of interest of the mandible cortical bone so that they become halftone, the mandible portion visibility improvement unit adjusts the shade of the normalized halftone, and the system control unit displays the image on the image display unit after normalization and shade adjustment to improve visibility.

5. A method for improving visibility of dental panoramic X-ray images to assist in the diagnosis of osteoporosis, as described in claim 4, characterized in that the step of determining the maximum pixel value of the mandibular cortical bone includes a step of calculating pixel values ​​for a predetermined region of interest including the mandibular cortical bone of the image in which the mandibular bone partial visibility improvement section is provided.

6. A program for improving visibility of dental panoramic X-ray images for supporting osteoporosis diagnosis, which program executes the method of claim 4 or 5.

7. A program storage medium storing the program according to claim 6 so as to be executable by the control unit of the panoramic X-ray image visibility improving system.

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