Image processing device, image processing method and program

Abstract

To enable the position of a detailed observation image to be appropriately set in a dental arch development image. [Solution] The image processing device includes a storage device that stores image data obtained by CT imaging of the tissues that constitute the dentition, a processing device, and a display device. The processing device generates three-dimensional image data of the tissues that constitute the dentition, identifies separable areas in the tissues that constitute the dentition, identifies three-dimensional positions of the separable areas in the coordinate system of the three-dimensional image, generates a dentition expansion image, identifies positions in the dentition expansion image that correspond to the separable areas, and displays on the display device the dentition expansion image in which the separable areas are displayed at the separable area corresponding positions. By specifying the separable area corresponding positions in the dentition expansion image, a detailed observation image of the separable area is generated based on the correspondence between the separable area corresponding positions and the three-dimensional positions, and a detailed observation reference position, which is a reference position for generating the detailed observation image, is determined according to predetermined rules.

Description

[Technical Field]

[0001] This disclosure relates to techniques for facilitating recognition of biometric feature regions. [Background technology]

[0002] Patent Document 1 discloses a technique for obtaining a panoramic tomographic image of the dentition using X-ray projection data of the dental and maxillofacial region obtained by X-ray CT imaging.

[0003] Patent Document 2 discloses a technique for displaying a detected region of interest on a CT scan image.

[0004] Patent Document 3 discloses a technology for detecting lesions by inputting CT images into a trained model. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-229322 [Patent Document 2] Special Publication No. 2021-528751 [Patent Document 3] Special Publication No. 2021-528751 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, for example, there is a case where it is required to provide detailed information on a part of the panoramic tomographic image disclosed in Patent Document 1. However, when specifying a position using a panoramic tomographic image, it is difficult to specify an appropriate position in the buccal-lingual direction.

[0007] Therefore, an object of the present disclosure is to enable the position of a detailed observation image to be appropriately set in a dentition expansion image. [Means for solving the problem]

[0008] The image processing device processes image data obtained by CT scanning of the tissues constituting the dentition to generate an image for diagnosis, and is equipped with a storage device that stores the image data, a processing device, and a display device that displays an image for observation based on the output of the processing device, and the processing device generates three-dimensional image data of the tissues constituting the dentition based on the image data, identifies a demarcable area in the tissues constituting the dentition based on the image data, identifies a three-dimensional position where the demarcable area exists in a coordinate system of the three-dimensional image, and generates an expanded image of the dentition in which the tissues constituting the dentition are expanded based on the three-dimensional image data. and specifies a position in the dental arch expanded image corresponding to the demarcable area that corresponds to the three-dimensional position, displays the dental arch expanded image in which the demarcable area is displayed at the position corresponding to the demarcable area on the display device, generates an image for detailed observation of the demarcable area from the three-dimensional image data by specifying the position corresponding to the demarcable area in the dental arch expanded image based on the correspondence between the position corresponding to the demarcable area and the three-dimensional position, determines a reference position for detailed observation that is a reference position for generating the image for detailed observation according to a predetermined rule, and displays the image for detailed observation on the display device.

[0009] The image processing method processes image data obtained by CT scanning of the tissues forming the dental arch to generate an image for diagnosis, and includes the steps of: generating three-dimensional image data of the tissues forming the dental arch based on the image data; identifying a separable area in the tissues forming the dental arch based on the image data; identifying a three-dimensional position where the separable area exists in the coordinate system of the three-dimensional image; generating an expanded image of the dental arch in which the tissues forming the dental arch are expanded based on the three-dimensional image data; identifying a position in the expanded image of the dental arch corresponding to the separable area that corresponds to the three-dimensional position; displaying the expanded image of the dental arch in which the separable area is displayed at the position corresponding to the separable area; generating a detailed observation image of the separable area from the three-dimensional image data by specifying the position corresponding to the separable area in the expanded image of the dental arch based on the correspondence between the position corresponding to the separable area and the three-dimensional position; determining a reference position for detailed observation, which is a reference position for generating the image for detailed observation, according to a predetermined rule; and displaying the image for detailed observation.

[0010] The program processes image data obtained by CT scanning of the tissues forming the dental arch to generate an image for diagnosis, and causes a computer to execute the following processes: generate three-dimensional image data of the tissues forming the dental arch based on the image data, identify the separable area in the tissues forming the dental arch based on the image data, identify the three-dimensional position where the separable area exists in the coordinate system of the three-dimensional image, generate an expanded image of the dental arch in which the tissues forming the dental arch are expanded based on the three-dimensional image data, identify a position in the expanded image of the dental arch corresponding to the separable area that corresponds to the three-dimensional position, display the expanded image of the dental arch in which the separable area is displayed at the position corresponding to the separable area, generate an image for detailed observation of the separable area from the three-dimensional image data based on the correspondence between the position corresponding to the separable area and the three-dimensional position by specifying the position corresponding to the separable area in the expanded image of the dental arch, determine a reference position for detailed observation which is a reference position for generating the image for detailed observation according to predetermined rules, and display the image for detailed observation. [Effects of the Invention]

[0011] According to the present disclosure, the position of the detailed observation image can be appropriately set in the dentition expansion image. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an image processing device and a CT imaging device according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the image processing device and the CT imaging device. [Figure 3] FIG. 3 is a functional block diagram of the arithmetic circuit. [Figure 4] FIG. 4 is a flowchart showing an example of processing by the image processing device. [Figure 5] FIG. 5 is an explanatory diagram showing the FOV region. [Figure 6] FIG. 6 is an explanatory diagram showing an example of a region where the tissues constituting the dentition spread. [Figure 7] FIG. 7 is an explanatory diagram showing the positional relationship between the tissues constituting the dentition and the separable area within the FOV region. [Figure 8] FIG. 8 is an explanatory diagram showing an example of coordinates of demarcable areas in the tissues constituting the dentition. [Figure 9] FIG. 9 is an explanatory diagram showing an example of processing for developing tissues constituting the dentition into an expanded image of the dentition. [Figure 10] FIG. 10 shows an expanded image of the dentition. [Figure 11] FIG. 11 is a diagram showing a display example of a dental arch development image and a detailed observation image. [Figure 12] FIG. 12 is a flowchart showing an example of a process for determining a reference position and an observation direction for detailed observation. [Figure 13] FIG. 13 is an explanatory diagram showing an example of specifying a position corresponding to a separable area using a dental arch development image. [Figure 14] FIG. 14 is an explanatory diagram showing an example of setting an image for detailed observation when the root apex is specified. [Figure 15] FIG. 15 is an explanatory diagram showing an example of setting an image for detailed observation when a root canal is specified. [Figure 16]FIG. 16 is a flowchart showing another example of processing for determining the reference position and observation direction for detailed observation. [Figure 17] FIG. 17 is an explanatory diagram showing an example of determining the observation direction using the dental arch curve. [Figure 18] FIG. 18 is an explanatory diagram showing an example of setting an image for detailed observation when a tooth is designated. [Figure 19] FIG. 19 is an explanatory diagram showing an example of setting the reference position in the buccal-lingual direction using a horseshoe-shaped frame. [Figure 20] FIG. 20 is a flowchart showing a specific example of the process of step S10 in FIG. [Figure 21] FIG. 21 is an explanatory diagram showing an example of a moving operation process for a detailed observation image. [Figure 22] FIG. 22 is a diagram showing an expanded image of a row of teeth according to the first modified example. [Figure 23] FIG. 23 is an explanatory diagram showing a state in which the head is positioned by the head holder. [Figure 24] FIG. 24 is an explanatory diagram showing the positional relationship between the head holding part and the tissues constituting the dentition. [Figure 25] FIG. 25 is a schematic diagram showing an image processing device according to a modified example. [Figure 26] FIG. 26 is a block diagram showing the electrical configuration of the image processing device. DETAILED DESCRIPTION OF THE INVENTION

[0013] {Embodiment} An image processing apparatus, an image processing method, and a program according to an embodiment will be described below.

[0014] <Configuration including image processing device and CT imaging device> FIG. 1 is a schematic diagram showing an image processing device 20 connected to a CT imaging device 10. As shown in FIG.

[0015] The CT imaging device 10 is a device that performs CT (Computed Tomography) imaging of the tissues that constitute the dentition to obtain image data. The obtained image data includes data related to the tissues that constitute the dentition. The image processing device 20 processes the image data to generate an image for diagnosis.

[0016] For example, a CT imaging device 10 includes an X-ray generator 11, an X-ray detector 12, a rotating arm 13, a support column 14, and an imaging processing unit 15. Three-dimensional coordinates are set for calculations in the space in which the CT imaging device 10 exists. The three-dimensional coordinates are set, for example, based on the orientation of a subject positioned for imaging, with a Z direction along the body axis, an X direction perpendicular to the Z direction and extending along the left-right direction of the subject, and a Y direction perpendicular to the Z direction and extending along the front-to-back direction of the subject. In this embodiment, the subject is positioned at the examination position in an upright position, and therefore the Z direction is perpendicular to the floor surface, along which the support column 14 extends.

[0017] The X-ray generator 11 includes an X-ray tube and is configured to emit an X-ray beam toward the subject. The X-ray detector 12 includes an X-ray detection sensor. The X-rays emitted from the X-ray generator 11 pass through the subject and are detected by the X-ray detector 12.

[0018] The rotating arm 13 is, for example, a member formed in a U-shape that opens downward. An X-ray generator 11 and an X-ray detector 12 are supported at both ends of the rotating arm 13 in an opposing state. A subject can be placed between the X-ray generator 11 and the X-ray detector 12. The subject is a part of the human body that includes tissues that form the dentition, i.e., the head including the jaw.

[0019] The support pillar 14 is erected so as to extend in the direction of gravity (vertical direction). A cantilever arm 14a is supported on the support pillar 14 so as to be movable up and down. A swivel arm 13 is rotatably supported on the cantilever arm 14a. The height position of the swivel arm 13 is adjusted along the support pillar 14 to match the height position of the head.

[0020] With the subject's head positioned between both ends of the rotary arm 13, the rotary arm 13 is rotated, causing the X-ray generator 11 and the X-ray detector 12 to rotate around the head, thereby performing X-ray CT imaging of the head and obtaining image data.

[0021] For example, when the rotating arm 13 rotates, X-ray imaging is performed at each small rotation angle. This allows X-ray projection image data (frame data) to be obtained for each small rotation angle. Three-dimensional volume data of the subject is generated based on a group of X-ray projection image data (frame data group) captured at different rotation angles. This three-dimensional volume data is three-dimensional image data that indicates the distribution of X-ray absorption rate of the subject in a three-dimensional coordinate system.

[0022] The CT imaging device 10 may include a head holder 9. The head holder 9 is a part that holds the head, which is the subject of imaging. The head holder 9 may include a chin rest 9a that supports the chin. The chin rest 9a can support the front and bottom of the chin of the head. This positions the head in a fixed position in the front-to-back and up-to-down directions. The head holder 9 may also include two side holders 9b that position the head from both sides. The two side holders 9b may be, for example, ear rods that contact both ears of the head. The two side holders 9b position the head in a fixed position in the left-to-right direction.

[0023] The image processing device 20 processes image data obtained by CT imaging to generate an image for diagnosis. The image data obtained by CT imaging may be a group of X-ray projection image data for each small rotation angle, or may be three-dimensional volume data. In this embodiment, an example will be described in which the image data obtained by CT imaging is a group of X-ray projection data for each small rotation angle.

[0024] The image processing device 20 comprises a processing unit 30, a display device 22, and user interfaces 24, 26.

[0025] The processing unit 30 is configured with a computer, a workstation, or the like. The processing unit 30 is connected to the imaging processing unit 15 of the CT imaging device 10 via a wired or wireless connection, and can transmit and receive various data to and from the imaging processing unit 15. In this embodiment, the processing unit 30 can receive image data obtained by CT imaging from the imaging processing unit 15. Some or all of the functions of the processing unit 30 may be realized by a cloud server.

[0026] The display device 22 is, for example, a liquid crystal display or an organic EL (electro-luminescence) display, and is connected by wire or wirelessly to the processing unit 30. The display device 22 can display an observation image for diagnosis based on the output for display of the processing unit 30.

[0027] The user interfaces 24, 26 are devices that accept instructions from a user of the image processing device 20. The user interface 24 may be, for example, a switch device such as a keyboard. The user interface 26 may be, for example, a pointer device such as a mouse. If the user interface is a switch device, the user's instructions can be input using the switch device alone. If the user interface is a pointer device, the user's instructions can be input by operating characters or images displayed on the display device 22. The user interface may be a touch panel.

[0028] <Electrical configuration of the image processing device and CT imaging device> FIG. 2 is a block diagram showing the electrical configuration of the image processing device 20 and the CT imaging device 10.

[0029] The CT imaging device 10 includes an imaging processing unit 15, an imaging unit driving mechanism 18, and a user interface 19.

[0030] The photographing processing unit 15 is composed of a computer including an arithmetic circuit 16 and a storage device 17 .

[0031] The arithmetic circuit 16 includes a processor 16a. The processor 16a may be a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit).

[0032] The storage device 17 is configured by a non-volatile storage device such as a flash memory or a hard disk drive. The storage device 17 may also be a memory circuit. The storage device 17 stores a program. The program describes the procedure for the CT imaging device 10 to perform CT imaging.

[0033] The imaging unit drive mechanism 18 is connected to the photographing processing unit 15. The imaging unit drive mechanism 18 includes a rotation drive mechanism for rotating the rotating arm 13. The rotation drive mechanism includes an actuator and a transmission mechanism. The actuator is an electric motor or the like that generates a rotation drive force. The transmission mechanism is gears, pulleys, or the like that transmit the rotation drive force of the actuator. The rotation drive force of the actuator is transmitted to the rotating arm 13 via the transmission mechanism, and the rotating arm 13 rotates at a timing and rotation speed according to a command from the photographing processing unit 15.

[0034] The user interface 19 is an interface for giving instructions to the CT imaging apparatus 10, and is a switch device, a pointer device, or the like. The user interface 19 is connected to the imaging processing unit 15. A user can give various instructions to the CT imaging apparatus 10 through the user interface 19.

[0035] The X-ray generator 11 and the X-ray detector 12 are also connected to the imaging processing unit 15. The X-ray generator 11 irradiates X-rays at the timing and output according to instructions from the imaging processing unit 15, and the X-ray detector 12 outputs the detection result to the imaging processing unit 15.

[0036] The processor 16a executes processing according to the program in the storage device 17, whereby the imaging unit drive mechanism 18 controls the rotation of the rotation arm 13 and also controls the X-ray irradiation operation of the X-ray generator 11. For each minute rotation angle of the rotation arm 13, the detection results of the X-ray detector 12 are input to the imaging processing unit 15, and the processor 16a generates X-ray projection image data for each minute rotation angle based on the detection results. The data 17a is stored in the storage device 17.

[0037] The image processing device 20 comprises a processing unit 30, a display device 22, and user interfaces 24, 26.

[0038] The processing unit 30 is connected to the display device 22 and the user interfaces 24, 26. The processing unit 30 can receive instructions from a user via the user interfaces 24, 26. The processing unit 30 can control the display of the display device 22.

[0039] The processing unit 30 is configured by a computer having an arithmetic circuit 32 as a processing device and a storage device 34 .

[0040] The arithmetic circuit 32 includes a processor 32a. The processor 32a may be a central processing unit (CPU). The processor 32a may include a graphics processing unit (GPU) or a processor for artificial intelligence (AI).

[0041] The storage device 34 is configured by a nonvolatile storage device such as a flash memory or a hard disk drive, or may be a memory circuit. The storage device 34 stores a program 34a and data 34b.

[0042] The program 34a describes a procedure for the image processing device 20 to process image data obtained by CT imaging and generate an image for diagnosis.

[0043] The data 34b includes image data transmitted from the CT imaging device 10 and data generated by the processing for generating the diagnostic image. After processing, the data 34b may be left as history data or may be deleted.

[0044] The processing unit 30 includes a connection port 36. The processing unit 30 is connected to the CT imaging device 10 through the connection port 36. The connection port 36 may include a terminal connected to a signal line of a wired cable extending from the CT imaging device 10 and a circuit for communication processing. The processing unit 30 and the CT imaging device 10 may be connected wirelessly, in which case the connection port 36 may include a circuit for wireless processing. The data 17a of the X-ray projection image data group from the CT imaging device 10 is transmitted to the processing unit 30 via the connection port 36 and stored in the storage device 34.

[0045] The arithmetic circuitry 32 reads the program 34a stored in the storage device 34 and executes the processes described in the program 34a, thereby enabling the arithmetic circuitry 32 to execute various processes for generating images for diagnosis, as will be described later. The processing unit 30 may also control CT imaging by the CT imaging device 10.

[0046] 3, the processing function unit realized by the arithmetic circuit 32 reading the program 34a may include a biological data processing unit 33. The biological data processing unit 33 may include a biological tissue data processing unit 33a and a demarcable area data processing unit 33b.

[0047] The biological tissue data processing unit 33a performs processing to generate three-dimensional data of the tissues constituting the dentition based on image data. The tissues constituting the dentition are, for example, tissues including the dentition and the alveolar bone. The tissues constituting the dentition may be tissues including the dentition and the jawbone. The jawbone in the tissues constituting the dentition may be the region of the jawbone that supports the teeth, and may include not only the alveolar bone but also its surrounding region. In this application, the alveolar bone is understood to be a partial region of the jawbone, the portion of the jawbone that forms the alveolus and supports the teeth. This understanding is in accordance with the explanation in the Encyclopedia of Dentistry. The tissues constituting the dentition may be horseshoe-shaped in a planar view. Note that the planar view may be considered as a planar view with the line of sight extending from the head to the feet in the axial direction of the body axis. The tissues constituting the dentition may extend to have a thickness in the buccolingual direction. The tissues constituting the dentition may be tissues that have at least the thickness of the dentition in the buccolingual direction. The tissues constituting the dentition may be tissues that have a thickness in the region of the jawbone that supports the teeth. The tissues constituting the dentition may include upper and lower dental arches and upper and lower jawbones supporting the upper and lower dental arches. Each of the upper and lower dental arches includes a plurality of teeth arranged in an arch. The upper jawbone has alveolar bone supporting the teeth of the upper dental arch. The lower jawbone has alveolar bone supporting the teeth of the lower dental arch.

[0048] The biological tissue data processing unit 33a, for example, identifies regions of each of the multiple teeth and regions of the upper and lower jawbone in the three-dimensional volume data. Identification of the tooth and upper and lower jawbone regions may be performed by applying a trained machine learning model. For example, a large amount of data in which regions of the teeth and upper and lower jawbone are mapped onto the three-dimensional volume data is prepared as training data. Using the training data, a machine learning model trained to segment the tooth regions and the upper and lower jawbone regions in the three-dimensional volume data is prepared. The machine learning model may be, for example, a model trained based on a semantic segmentation algorithm. By applying the trained machine learning model to the three-dimensional volume data, regions of the multiple teeth and regions of the upper and lower jawbone are identified in the three-dimensional coordinate system. As a result, the tooth row region and the alveolar bone region are distinguished based on the three-dimensional volume data.

[0049] The regions of the plurality of teeth and the regions of the upper and lower jaw bones in the three-dimensional volume data may be identified by a region extraction process according to a predetermined rule, such as a pattern matching process.

[0050] The demarcable area data processing unit 33b is a process for identifying demarcable areas in the tissues constituting the dentition based on image data. The demarcable areas in the tissues constituting the dentition are parts that can be separated from other parts in the tissues constituting the dentition based on image data obtained by CT imaging. For example, the demarcable areas are parts that are separated based on the presence or absence of real objects in the tissues constituting the dentition or differences in X-ray absorption rates. The demarcable areas may be a widespread area or a localized location.

[0051] The demarcable area may be, for example, an anatomical demarcation area. An anatomical demarcation area is an area where the tissues that make up the dentition are anatomically demarcated. More specifically, the anatomical demarcation area may be each of a plurality of teeth, or each of the upper and lower jawbones. The anatomical demarcation area may be each of the root canals or root apices of a plurality of teeth. The anatomical demarcation area may be the mandibular canal.

[0052] When the demarcable area is an anatomical demarcable area, some or all of the processing performed by the demarcable area data processing unit 33b may be performed by the biological tissue data processing unit 33a. For example, identification of multiple teeth and jawbones may be performed by the biological tissue data processing unit 33a, and processing to identify the root canal, root apex, or mandibular canal in the teeth or jawbones may be performed by the demarcable area data processing unit 33b. In other words, when the demarcable area includes teeth and jawbones, it may be considered that the biological tissue data processing unit 33a identifies the demarcable area in the tissues constituting the dentition for the teeth and jawbones at the same time as generating three-dimensional image data of the tissues constituting the dentition based on the image data.

[0053] The demarcable area may be, for example, a biological characteristic area in the tissues that make up the dentition. The biological characteristic area may be, for example, a region in the tissues that make up the dentition where a lesion has occurred. A lesion is a change caused by a disease. A region in which a lesion has occurred exhibits a distribution of X-ray attenuation that differs from the distribution of X-ray attenuation exhibited by normal tissues that make up the dentition. Examples of diseases include chronic suppurative apical periodontitis and root granuloma. In the case of apical periodontitis, a region in the periphery of the tip of the tooth root exhibits lower X-ray attenuation than the normal state and its surroundings. Therefore, apical periodontitis can be identified when a low X-ray attenuation area is present around the periphery of the tooth root. For other lesions, the region in which the lesion has occurred can be identified based on three-dimensional volume data obtained by CT imaging, based on the position in the tissues that make up the dentition, such as the tooth or jawbone, the spread pattern or distribution pattern of the X-ray attenuation area, and the like. Here, if the demarcable area is, for example, multiple lesion areas, the collection of demarcable areas is naturally composed of the individual lesion areas. An individual demarcable area that constitutes a collection of demarcable areas, such as this individual lesion area, may be called a unitary demarcable area. An area where multiple unitary demarcable areas are collected may be called a collective demarcable area. An image of a demarcable area may be called a demarcable area image.

[0054] The separable area data processing unit 33b may identify the separable area by applying a trained machine learning model similar to that used to identify the tissues that constitute the dentition. For example, a large amount of data in which the separable area is mapped onto 3D volume data is prepared as training data. Using the training data, a machine learning model is prepared that is trained to segment the separable area in the 3D volume data. The trained machine learning model is applied to the 3D volume data to identify the separable area in the 3D coordinate system.

[0055] The identification of the separable area in the three-dimensional volume data may be performed by an image extraction process, for example, a pattern matching process.

[0056] The identification of the separable area does not have to be based on the three-dimensional volume data. For example, the separable area may be identified by applying a machine learning model or pattern matching based on slice data obtained by slicing the three-dimensional volume data in any direction.

[0057] In this embodiment, an example will be mainly described in which the demarcable area is an anatomical demarcable area included in the tissues that constitute the dentition.

[0058] <Processing unit processing example> An example of processing by the processing unit 30 will be described with reference to the flowchart of FIG.

[0059] After starting the process, in step S1, the processing unit 30 acquires captured image data from the CT imaging device 10. The captured image data is, for example, data of a field of view (FOV) region including the dental arch Ht and jawbone Hj of the head H (see FIG. 5). The FOV may be set to, for example, a cylindrical region, an elliptical cylindrical region, or a triangular prism region.

[0060] In the next step S2, the processing unit 30 generates three-dimensional volume data based on the captured image data.

[0061] In this embodiment, in step S1, the captured image data acquired from the CT imaging device 10 is a group of X-ray projection image data. In step S2, three-dimensional volume data is generated based on the group of X-ray projection image data. The three-dimensional volume data may be generated based on the group of X-ray projection image data in the CT imaging device 10. In this case, the processing unit 30 may acquire the three-dimensional volume data as image data.

[0062] It is also possible that the CT imaging device 10 generates multiple tomographic images based on a group of X-ray projection image data. In this case, the processing unit 30 may acquire multiple tomographic images as image data from the CT imaging device 10 and generate three-dimensional volume data by superimposing the multiple tomographic images.

[0063] In the next step S3, the processing unit 30 executes a process of generating three-dimensional image data of the structures that constitute the dentition based on the image data, and a process of identifying a separable region L in the structures that constitute the dentition based on the image data.

[0064] As shown in FIG. 6, the area Ee in which the tissues constituting the dentition E extend includes the dental arch Ht in which multiple teeth T are arranged, and the upper and lower jawbones Hj, as described above. The tissues constituting the dentition may also include the temporomandibular joint Hjo. In the three-dimensional volume data, the area Ee in which the tissues constituting the dentition E extend may be called the tissues constituting the dentition area Ee. The tissues constituting the dentition area Ee is a horseshoe-shaped area that is set by calculation, and it may be any area that fits the shape and position of the tissues constituting the dentition. The horseshoe-shaped frame F described below is an example of the tissues constituting the dentition area Ee. The shape of the tissues constituting the dentition area Ee may be one that fits the shape of the tissues constituting the dentition E of a standard skeleton, and if the shape of the tissues constituting the dentition E of an individual is known, it may be set to a shape that fits that individual.

[0065] As described above, the process of generating three-dimensional image data of the tissues that make up the dentition based on image data may also be a process of identifying each region of a plurality of teeth and each region of the upper and lower jaw bones based on three-dimensional volume data, and combining these regions to generate three-dimensional data of the tissues that make up the dentition.

[0066] Each region of the multiple teeth and each region of the upper and lower jawbones may be identified by the surface of the teeth and jawbones, i.e., the boundaries between the interior and exterior of the teeth and jawbones. The planes formed by the boundaries may be considered surfaces. In other words, each region of the multiple teeth and each region of the upper and lower jawbones may be identified as the surface shapes of each tooth and jawbone in the three-dimensional coordinate system of the three-dimensional volume data. Functional tissues that constitute a living body, such as teeth and jawbones, may be called functionally-specific tissues constituting the dentition. For example, teeth are functionally-specific tissues constituting the dentition that have the function of chewing food, and jawbones are functionally-specific tissues constituting the dentition that have the function of supporting the teeth. The tissues constituting the dentition may be considered to include multiple functionally-specific tissues constituting the dentition. Because the region of the jawbone boundary facing the teeth is important, a learning model including segmentation of the alveolar inner wall may be prepared to enable highly accurate detection of the alveolar inner wall.

[0067] Furthermore, the process of identifying the demarcable area based on image data may be the process of identifying the demarcable area in the tissues that constitute the dentition based on three-dimensional volume data, as described above. In this embodiment, an example will be described in which the demarcable area is an anatomical demarcable area.

[0068] The separable area may be specified by the surface of the tooth and jawbone, that is, the boundary between the inside and outside of the tooth and jawbone, just like the above-mentioned areas of the tooth and jawbone. The plane formed by the boundary may be considered to be the surface. The separable area may be a long and narrow part such as a root canal, or an extremely small part such as a root apex, so it may be specified by a straight line, curve, or point in three-dimensional coordinates. The specification of the separable area may be considered as a distinction between areas that are separable and areas that are not.

[0069] In step S3, three-dimensional image data of the dentition-forming tissues E, including the dentition and jawbone, is generated within the FOV, and a separable region L in the dentition-forming tissues E is identified (see FIG. 7). In FIG. 7, some of the separable regions L are illustrated.

[0070] In this embodiment, the explanation is given on the assumption that some sort of separable region exists. If no separable region is identified, the processing may end.

[0071] In step S4, the processing unit 30 calculates the three-dimensional position where the identified demarcable area exists in the coordinate system of the three-dimensional image data of the dentition-forming tissues E. The three-dimensional coordinates of the three-dimensional image data are set based on the spatial coordinates of the CT imaging device, for example, the X1 direction, which is the same as the X direction, the Y1 direction, which is the same as the Y direction, and the Z1 direction, which is the same as the Z direction, based on the orientation of the subject at the time of imaging. The three-dimensional position of the demarcable area may be the coordinates themselves that identify the demarcable area identified in step S3. For example, it may be a group of three-dimensional coordinates that represent the surface of the demarcable area. The three-dimensional position where the demarcable area exists may be called the three-dimensional position of the demarcable area.

[0072] The three-dimensional position of the demarcable area may be coordinates calculated based on the demarcable area identified in step S3. For example, if the demarcable area is a biometric feature area, the three-dimensional position of the demarcable area may be the coordinates of a point located within the boundary of the biometric feature area. The coordinates of the biometric feature area may be, for example, the geometric center of the surface of the lesion area detected in step S3 (see FIG. 8). They may also be any position on the surface of the lesion area (for example, the lower end or upper end).

[0073] In the next step S5, the processing unit 30 determines whether or not there is a command to display an unfolded image. The command to display an unfolded image is accepted using the user interfaces 24, 26. When the user inputs a command to display an unfolded image using the user interfaces 24, 26, the processing unit 30 determines that there is a command to display an unfolded image, and proceeds to step S6. When the user does not input a command to display an unfolded image, the processing unit 30 determines that there is no command to display an unfolded image, and proceeds to step S13.

[0074] In step S13, the processing unit 30 determines whether or not there is another command via the user interface 24, 26, etc. If it is determined that there is another command, the processing unit 30 executes the other process. If it is determined that there is no other command, the process returns to step S5, and the processing unit 30 repeats the process of determining whether or not there is a command to display the unfolded image.

[0075] When the process proceeds to step S6, the processing unit 30 generates a dentition expanded image Ep by expanding the dentition-forming tissues E based on the three-dimensional image data of the dentition-forming tissues E. The dentition expanded image Ep is an image in which the dentition-forming tissues E, which are arch-shaped or horseshoe-shaped in plan view, are expanded to form a straight line in plan view (see FIG. 9). For example, the dentition expanded image Ep is generated as follows: At each coordinate position in the vertical direction, a curve forming an arch or horseshoe shape that passes through the center of the dentition-forming tissues E in the buccolingual direction is calculated. At each position along the curve, the presence or absence or transparency of an image of the dentition-forming tissues E in a direction perpendicular to the tangent to the curve is calculated. The presence or absence or transparency of an image at each coordinate on the curve is expressed as the presence or absence of an image at each coordinate on the line. The dentition expanded image Ep is generated by performing the above process at each coordinate position in the vertical direction and overlapping them in the vertical direction.

[0076] In addition, when the three-dimensional image data of the dental arch-forming tissues E is represented by semi-transparent data of the surface of the dental arch-forming tissues E, the areas that are the boundaries of the dental arch-forming tissues in the dental arch expanded image Ep are represented with low transparency and in dark colors.

[0077] The dentition expansion image Ep is a type of panoramic image in which the dental arch is expanded in a plane. The dentition expansion image Ep may also include the alveolar bone. The dentition expansion image Ep may also include the jawbone. The dentition expansion image Ep may be an image of the dentition-constituting tissues E transmitted through the thickness direction, or may be a tomographic image of an arbitrary position in the thickness direction.

[0078] The dentition expanded image Ep may be an image obtained by viewing the entire area of ​​the tissues constituting the dentition E in a normal view. An image obtained by viewing the entire area of ​​the tissues constituting the dentition E in a normal view is an image obtained by viewing the entire tissues constituting the dentition E from in front of the midline of the head H (from a normal viewing direction Dv that views the anterior tooth region normal) when the dentition expanded image Ep is expanded in a direction perpendicular to the midline Md of the head H, as shown in Fig. 9.

[0079] The dentition expanded image Ep may be superimposed not only with 3D image data of the dentition-forming structures E but also with data obtained by converting 3D volume data into a panoramic image. The dentition expanded image Ep does not necessarily have to be expanded to form a straight line in a planar view, and may include curvature or refraction. In other words, the dentition expanded image Ep may be an image that allows the entire dentition-forming structures E to be observed at a glance. For example, the expansion may be processed so that the left and right end regions of the dentition-forming structures region Ee are displaced more anteriorly than the central region. A linear or nearly linear expansion in a planar view is referred to as "flat expansion," and the dentition expanded image Ep may be an image that is flatly expanded. The image process for generating the dentition expanded image Ep so that the entire dentition-forming structures E can be observed at a glance may be called an expansion process. In particular, a flat expansion process may be called a flat expansion process. A flat expansion may also be called a flat expansion.

[0080] By similarly applying the above process to the separable area L, a separable area corresponding position P2 corresponding to the above three-dimensional position P1 is calculated in the dentition expanded image Ep. The separable area corresponding position P2 may be considered to be a position obtained by transforming the three-dimensional position P1 of the separable area identified in step S4 using the same geometric transformation process as the one used to expand the dentition-constituting structures E into the dentition expanded image Ep. The three-dimensional position P1 can be determined, for example, by a group of coordinates expressing the surface of the separable area, or by representative coordinates indicating the separable area. The representative coordinates of the separable area may be a center, for example, a geometric center or a center of gravity.

[0081] The three-dimensional position P1 may be the position of a point (i.e., the position indicating a specific point) as the calculation target, but if the demarcable area has a large area, it may be the position of at least a part of that area. For example, a certain area around the center including the center is conceivable. The three-dimensional position P1 may also be the position of the entire demarcable area. Therefore, the corresponding position P2 may also be the position of a point or the position of an area as the calculation target.

[0082] The area set by calculation when the dentition tissue area Ee is expanded may be considered to be the dentition expanded area Ex. A flat expansion of the dentition tissue area Ee may also be called a flat expansion, and in particular, the flatly expanded dentition expanded area Ex may be considered to be the dentition flat expanded area Exp.

[0083] The expansion of the tissues forming the dentition E may be performed by an expansion process that expands the image data of the tissues forming the dentition area Ee so that it fits the shape of the dentition expanded area Ex. In the following discussion, it is assumed that the area occupied by the tissues forming the dentition E and the tissues forming the dentition area Ee match, and that the area occupied by the dentition expanded image Ep matches the dentition expanded area Ex.

[0084] The state of the dentition-constituting tissue region Ee before expansion may be called the pre-expansion curved state, and the state of the dentition expansion region Ex after expansion may be called the post-expansion view state. The expansion process is preferably performed so that the buccolingual direction BLD in the pre-expansion curved state corresponds to the normal view direction NVD in the post-expansion view state.

[0085] The normal viewing direction may be a direction perpendicular to or normal to the normal plane of the dentition spread area Ex, but a viewing direction based on another concept may also be set. For example, a virtual viewpoint Ey1 may be set in the normal viewing direction at the center of the dentition spread area Ex, and image processing may be performed along the viewing direction EVD from this viewpoint.

[0086] In the dentition spread area Ex and / or the dentition spread image Ep, an area that exists at the demarcable area corresponding position P2 and corresponds to the demarcable area L may be called a demarcable area corresponding area Lc.

[0087] Since the dentition tissue region Ee has a thickness in the buccolingual direction, the dentition expanded region Ex also has a thickness in the normal viewing direction corresponding to the thickness in the buccolingual direction. Furthermore, since the dentition tissue E has a thickness in the buccolingual direction as described above, the dentition expanded image Ep also has a thickness in the normal viewing direction corresponding to the buccolingual direction.

[0088] Since the dentition expansion area Ex has a thickness corresponding to the dentition-forming tissue area Ee, unlike a thin panoramic tomography, even if the position of the separable area is biased in the buccolingual direction, it can be contained within the area (in image processing, the separable area image can be contained within the area without blurring). The coordinates of the three-dimensional position P1 may be calculated as coordinates within the FOV area, or as coordinates within the dentition-forming tissue area Ee.

[0089] In the expansion, a calculation may be performed to associate the three-dimensional position P1 of the demarcable area with the demarcable area corresponding position P2. The calculation to perform this correspondence may be called an original coordinate calculation. The original coordinate calculation may include a calculation to identify the position of the three-dimensional position P1 of the demarcable area in the buccolingual direction. Also, a calculation may be performed to identify the position of the demarcable area corresponding position P2 in the normal viewing direction corresponding to the buccolingual direction.

[0090] Then, as shown in FIG. 10, the processing unit 30 displays on the display device 22 the row of teeth expanded image Ep in which the demarcable area L is displayed at the position corresponding to the demarcable area.

[0091] For calculation purposes, three-dimensional coordinates may be set for the dentition spread area Ex. For example, the direction of left-right extension of the dentition spread area Ex when unfolded is defined as the R direction. The direction parallel to the body axis is defined as the T direction. In this embodiment, the T direction, Z direction, and Z1 direction are the same. The direction parallel to the normal viewing direction is defined as the S direction. In the dentition spread image Ep, the left-right direction is defined as the R direction, and the up-down direction is defined as the T direction. Once the conditions for specifying the RT coordinate on the dentition spread image Ep and the S direction are determined, it becomes possible to mutually identify the X1Y1Z1 coordinate. Therefore, in areas where both the RT coordinate and the S coordinate are determined, such as the demarcable area corresponding area Lc in the dentition spread area Ex, it is possible to mutually identify the X1Y1Z1 coordinate of the demarcable area L. Coordinates on three-dimensional image data, such as X1Y1Z1 coordinates, may be called three-dimensional image data coordinates, and three-dimensional coordinates may be called three-dimensional image data three-dimensional coordinates. Coordinates on the dentition spread area Ex, like the RST coordinates, may be called dentition spread area coordinates, and the three-dimensional coordinates may be called dentition spread area three-dimensional coordinates.

[0092] The separable area L displayed in the dentition expansion image Ep may be represented by the boundary of the separable area L. For example, the boundary between the teeth and the jawbone as the separable area L may be shown by a line. The separable area may be represented by a line or a representative point. If the separable area is an extremely small part such as the root apex and is difficult to notice, the separable area may be indicated by a different brightness or color from other parts, by a distinctive mark, or by a blinking display.

[0093] In the example shown in Figure 10, the boundaries of the teeth and jawbone as the separable area L are indicated by lines, and the root apices are indicated by round marks. The semi-transparent processing of the functional dentition tissues may be performed by forming the boundaries of the functional dentition tissues with uniform, sparse dots, as in the tooth image THd. This results in high transparency in the area Or perpendicular to the line of sight, and low transparency in the area Bd along the line of sight, making the boundaries easy to see despite the translucency. The dots may be non-uniform to the extent that they do not cause visual difficulties. As long as the boundary surface is transparent, image processing is not limited to dots; see-through surfaces such as meshes may also be used. Whether using dots or a mesh, the transparency changes depending on the line of sight due to the varying density. Image processing that changes transparency depending on the line of sight may be called line of sight-dependent transparency image processing.

[0094] An element whose transparency is increased, such as a dot that has become sparse compared to a dense state or a dot that has disappeared, is called a parent transparent element. In addition, increasing transparency is called parent transparency.

[0095] An element that reduces transparency, such as a dense dot compared to a sparse or non-existent state, is called an anti-transparency element. Also, reducing transparency is called anti-transparency.

[0096] The gaze direction compatible image processing for making transparent may be a combination of at least one of the following group A and at least one of the following group B. Group A: · Processing to enlarge or increase the parent transparency element of the normal boundary surface -Processing to promote parent transparency at the boundary of normal vision Treatment to reduce, diminish or eliminate the anti-transparency elements of the normal vision interface Treatment to suppress anti-transparency of the normal vision interface Group B: - Processing to reduce, decrease or eliminate parent transparency elements on the boundary surface of oblique or side views - Processing to suppress parent transparency at the boundary surface of oblique or side views Treatment to enlarge or increase the anti-transparency factor at the oblique or lateral viewing interface Treatment to promote anti-transparency at the interface of oblique or lateral vision The alveolar bone and jawbone portions may also be subjected to gaze direction-compatible transparent image processing.

[0097] Step S5 may be omitted, and after the processing of step S4 is completed, the processing of step S6 may be performed regardless of whether or not a command is issued.

[0098] In the next step S7, the processing unit 30 determines whether a display object has been designated. The display object is designated by designating a demarcable corresponding position in the dentition expanded image Ep. The demarcable corresponding position may be designated by selecting one of the multiple demarcable areas L using, for example, a selection switch on a keyboard or a pointer device such as a mouse. The demarcable corresponding position may be designated by designating a position in one of the demarcable areas using a pointer device such as a mouse. The processing of step S7 is repeated until a display object is designated, and once the display object is designated, the processing proceeds to the next step S8.

[0099] In steps S8 and S9, a detailed observation image D of the separable area is generated from the 3D image data based on the correspondence between the separable area corresponding position and a three-dimensional position (the separable area three-dimensional position) using the separable area corresponding position specified in step S7, and is displayed. Then, the detailed observation image D is displayed on the display device 22 simultaneously with the row of teeth expanded image Ep (see FIG. 11). An image Q indicating the specified position may be added to the row of teeth expanded image Ep. In FIG. 11, a circular mark larger than the mark indicating the root apex is added. The image Q indicating the specified position may be an image that exhibits a color, shape, or change that is distinguishable from the row of teeth expanded image Ep that spreads in the background. For example, the image Q may be an image that exhibits a different color from the row of teeth expanded image Ep. More specifically, the image Q may be an image that exhibits a noticeable warm color, such as red, orange, or yellow. The image Q may also be an image that exhibits a change in display, such as blinking, color change, or shape change, that distinguishes it from the row of teeth expanded image Ep. The image Q may have a shape that can be distinguished from the dentition development image Ep, such as a circle, a regular polygon, a radial shape, a cross shape, or an exclamation mark shape.

[0100] The detailed observation image D is an image that allows for more detailed observation than the dentition expansion image Ep and is suitable for more detailed diagnosis. In this embodiment, an example will be described in which the detailed observation image D includes multiple cross-sectional images Da, Db, and Dc, more specifically, three cross-sectional images Da, Db, and Dc that are orthogonal to each other (see FIG. 11).

[0101] The cross-sectional images are preferably cross sections passing through a detailed observation reference position Ps suitable for detailed observation of the separable area. The three cross-sectional images Da, Db, and Dc may be cross sections in planes that pass through the detailed observation reference position Ps and are perpendicular to each other. The three cross-sectional images Da, Db, and Dc may be cross sections centered on the detailed observation reference position Ps. The center here may be the geometric center or the center of gravity.

[0102] In the three-dimensional image data of the dentition-forming tissues E, a plane passing through the detailed observation reference position Ps is identified, and the distribution of X-ray transmittance along that plane is calculated to generate three cross-sectional images Da, Db, and Dc. The three cross-sectional images Da, Db, and Dc may be the distribution of X-ray transmittance in a thick slice layer. The correspondence between the three-dimensional position P1 of the demarcable area and the demarcable area corresponding position P2 is determined in the calculation of the unfolding process, so it is also determined which coordinates of the three-dimensional position P1 correspond to in the FOV area and / or which coordinates of the dentition-forming tissue area Ee they correspond to. The same applies to the coordinates of each point in the area shown in the dentition-forming unfolded image Ep. Of course, the original coordinate calculation described above may be performed.

[0103] The correspondence between the three-dimensional position P1 of the separable area and the separable area corresponding position P2 is determined by the calculation of the unfolding process. Therefore, if the coordinates in the up-down and left-right directions belonging to the separable area can be specified in the dentition exfoliated image Ep, it can be determined where the specified position in the dentition exfoliated image Ep is located in the tangential direction of the dental arch and in the up-down direction in the three-dimensional coordinate system.

[0104] For example, in step S6, when a dental arch expanded image Ep is generated by expanding the dental arch-forming structures E based on the three-dimensional image data of the dental arch-forming structures E, the three-dimensional position P1 of the separable area is converted into a separable area-corresponding position P2. This correspondence is stored as a table in the storage device 34. By referring to the table, it is possible to identify where a position specified in the dental arch expanded image Ep is located in the tangential direction and up-down direction of the dental arch in the three-dimensional coordinate system. Alternatively, it is also possible to identify where a position specified in the dental arch expanded image Ep is located in the tangential direction and up-down direction of the dental arch in the three-dimensional coordinate system in the inverse transformation process of the geometric transformation process that expands the dental arch-forming structures E into the dental arch expanded image Ep.

[0105] However, when specifying a position on the dentition expansion image Ep, it may be difficult to specify a position in the buccal-lingual direction. For example, even if the separable area is a tooth and a tooth on the dentition expansion image Ep is specified, it is unclear which position in the buccal-lingual direction has been specified. Therefore, it is difficult to identify the reference position Ps for detailed observation in the three-dimensional coordinate system.

[0106] Therefore, in step S8, the detailed observation reference position Ps, which is the reference position for generating the detailed observation image D, is determined in accordance with a predetermined rule. The rule may be a constant rule regardless of the type of the demarcable area, or may be a rule for each type. Examples of the rule will be explained in more detail later.

[0107] Furthermore, in step S8, the observation directions of the cross-sectional images Da, Db, and Dc are determined. The directions of the cross-sectional images Da, Db, and Dc may be any direction. For example, the three cross-sectional images Da, Db, and Dc may include a cross-sectional image Dc perpendicular to the buccal-lingual direction, a cross-sectional image Db perpendicular to the body axis direction, and a cross-sectional image Da perpendicular to both the cross-sectional images Dc and Db. The cross-sectional image Dc perpendicular to the buccal-lingual direction may be a cross section along the tangent direction of a curve along the extension direction of the tissues E constituting the dentition. The cross-sectional image Da perpendicular to the buccal-lingual direction is an example of a cross-sectional image that provides a square view of the separable area. As the default cross sections, which cross-sectional images are assigned to which roles can be arbitrarily determined. Therefore, among the cross-sectional images Da, Db, and Dc, the cross-sectional image perpendicular to the buccal-lingual direction, the cross-sectional image perpendicular to the upper and lower body axis directions, and the cross-sectional image perpendicular to both of these cross-sectional images can be appropriately changed.

[0108] The observation direction is a direction that is orthogonal to the cross-sectional images Da, Db, and Dc and in which the observer observes the cross-sectional images Da, Db, and Dc. The observation direction of the cross-sectional images Da, Db, and Dc may also be determined based on position information of the demarcable area. An example of determining the observation direction based on position information of the demarcable area will be described in more detail later. Note that the directions of the cross-sectional images Da, Db, and Dc are directions that are orthogonal to the respective cross sections, and the observation direction is the direction in which the observer observes the cross-sectional images Da, Db, and Dc.

[0109] The detailed observation image D may be, for example, a cross-sectional image with a higher resolution than the dentition development image Ep. The detailed observation image D may be a three-dimensional image whose line of sight is changeable.

[0110] As a result, in step S9, a detailed observation image D is generated that corresponds to the position in the demarcable area designated as the display target through the user interfaces 24, 26 based on the detailed observation reference position Ps.

[0111] It is preferable that the image for detailed observation D is displayed on the display device 22 simultaneously with the expanded image of the row of teeth Ep. In this case, the position of the image for detailed observation D relative to the expanded image of the row of teeth Ep is arbitrary. In Fig. 11, the expanded image of the row of teeth Ep and the image for detailed observation D are arranged side by side. The expanded image of the row of teeth Ep and the image for detailed observation D may also be arranged side by side vertically. The image for detailed observation D may also be displayed superimposed on the expanded image of the row of teeth Ep, partially entering the expanded image of the row of teeth Ep.

[0112] Furthermore, the layout of the cross-sectional images Da, Db, and Dc in the detailed observation image D is arbitrary. In Fig. 11, the rectangular display area of ​​the detailed observation image D is divided into two parts, vertically and horizontally. The cross-sectional image Dc orthogonal to the buccal-lingual direction is displayed in the lower right area, the cross-sectional image Db orthogonal to the body axis direction is displayed in the upper left area, and the cross-sectional image Da orthogonal to those is displayed in the lower left area.

[0113] Each of the three cross-sectional images Da, Db, and Dc may include an index Li indicating the position of the other cross-section. The index Li may be a straight line, a dashed line, a short line located in the central region of the cross-sectional images Da, Db, and Dc, or two marks located on the periphery of the cross-sectional images Da, Db, and Dc. In other words, the index Li may be any indication that can indicate the linear position of the other cross-section. In FIG. 11, each of the cross-sectional images Da, Db, and Dc includes a vertical line and a horizontal line as the index Li, which indicate the position of the other cross-section.

[0114] When a display object is designated by processing steps S7 to S9, a process of automatically displaying the detailed observation image D corresponding to the designated display object is automatically executed.

[0115] Note that even if a display target is not specified, a detailed observation image D corresponding to any one of the disjoint areas may be automatically displayed. The disjoint area for which the detailed observation image D is initially displayed may be a randomly selected characteristic area, or may be the characteristic area closest to a reference position such as the upper left.

[0116] In the next step S10, the processing unit 30 performs processing for display related to an adjustment operation, which will be described later, on the detailed observation image D. Specifically, step S10 is processing whose main contents range from step S50, which is the start step of processing related to an adjustment operation for an image for detailed observation, which will be described later, to step S53, which is a step for generating and displaying an image for detailed observation after adjustment.

[0117] In the next step S11, the processing unit 30 determines whether or not another display object has been designated through the user interface 24, 26. The designation of another display object may be performed in the same manner as described in step S7. If it is determined that another display object has been designated, the process returns to step S8, and the subsequent processes are repeated. If it is determined that another display object has not been designated, the process proceeds to step S12, where it is determined whether or not the processing for diagnosis has been terminated. If an input indicating that the processing has been terminated is received through the user interface 24, 26, etc., the processing is terminated. If the processing has not been terminated, the process returns to step S11, and if no other display object has been designated, the processing of step S12 is repeated.

[0118] The designation of the display object is the designation of a position corresponding to a demarcable area. The designation of a position corresponding to a demarcable area can be considered to be the designation of any one of a plurality of demarcable areas. The designation of a position corresponding to a demarcable area can also be considered to include the designation of a coordinate position within the designated demarcable area in the two-dimensional coordinate system of the tooth row expanded image Ep.

[0119] <Example of process for determining reference position and cross-sectional direction for detailed observation> A more specific example of the processing in step S8 will be described with reference to the flowchart shown in Fig. 12. Here, an example will be described in which the detailed observation reference position Ps and cross-sectional direction are determined for each type of separable area.

[0120] As a premise, as shown in FIG. 13, the three-dimensional positions P1 of the tooth T, jawbone Hj, root canal Ra, and root apex Rb are identified as the separable area L, and the separable area corresponding positions P2 of the tooth T, jawbone Hj, root canal Ra, and root apex Rb are also identified in the dental arch expansion image Ep.

[0121] The root apex Rb is located in a limited area, so its three-dimensional position P1 is specified by the coordinates of a representative point. The root canal Ra is an elongated part, so its three-dimensional position P1 may be specified by a line. The tooth T and the jawbone Hj have their three-dimensional positions P1 specified by surface data or data representing a solid body with a filled interior.

[0122] When a display object is designated using the user interfaces 24, 26, the type of the designated object is determined in step S21. The types are classified into the tooth T, jawbone Hj, root canal Ra, root apex Rb, which are identified as separable areas, and others. For example, whether a position designated by a key or mouse on the dentition expansion image Ep belongs to one of the tooth T, jawbone Hj, root canal Ra, root apex Rb, or other areas is determined to determine whether it belongs to one of the above types. Rules for determining the detailed observation reference position Ps are set in advance for each of the above types and are incorporated into the processing of steps S22, S24, S26, and S29.

[0123] If it is determined in step S21 that the target is the root apex Rb, the process proceeds to step S22 (see arrow Ar1 in FIG. 13).

[0124] In step S22, a reference position is identified based on the three-dimensional position P1 of the root apex Rb. That is, when any root apex Rb is identified in the dentition expansion image Ep, the three-dimensional position P1 corresponding to that root apex Rb is identified (see FIG. 14). Because the root apex Rb exists in a limited location, the three-dimensional direction is identified by the coordinates of a representative point. Therefore, the three-dimensional position P1 of that root apex Rb can be used as the reference position Ps for detailed observation.

[0125] Step S22 is an example of processing performed according to a rule for determining the detailed observation reference position Ps based on position information of at least a part of the root apex Rb, which is a separable area.

[0126] In the next step S23, an observation direction is determined based on the direction of the root canal Ra and the dental arch. For example, since the root apex Rb is located at the tip of the root canal Ra, the root canal Ra that is the origin of the specified root apex Rb can be identified based on the three-dimensional position of the root apex Rb and the three-dimensional position of the root canal Ra. Then, the root canal direction Rad in which the root canal Ra extends can be identified based on data indicating the line that is the three-dimensional position of the root apex Rb.

[0127] Furthermore, at each coordinate position in the vertical direction, a curve in the shape of an arch or a horseshoe that passes through the center of the dental arch-constituting tissues E in the buccolingual direction, i.e., the dental arch curve, is calculated (see FIG. 17). The tangential direction Rae is calculated at the position of the dental arch curve that is closest to the detailed observation reference position Ps. The tangential direction Rae may directionally coincide with the tangential direction Tc in FIG. 17 described below. The direction perpendicular to both the root canal direction Rad and the tangential direction Rae is defined as the bi-orthogonal direction Raf. Because the root canal direction Rad is often roughly parallel to the body axis, the bi-orthogonal direction Raf often coincides with or nearly coincides with the buccolingual direction.

[0128] For example, the observation directions of the three cross-sectional images Da, Db, and Dc can be set to the bi-orthogonal direction Raf, the root canal direction Rad, and the tangential direction Rae.

[0129] The bi-orthogonal direction Raf is preferably a direction in which the target area is viewed from the outside to the inside. The root canal direction Rad may be a direction toward the jawbone or a direction away from the jawbone. The tangential direction Rae may be a direction toward the right or a left.

[0130] In each of the following examples, the observation direction of each cross section is preferably a direction in which the target area is viewed directly from the outside to the inside in the buccal-lingual direction, and may be any direction in the vertical and horizontal directions.

[0131] By determining the observation direction based on the direction of the root canal Ra in this way, the observation direction of the detailed observation image D is determined based on the position information of at least a part of the root canal Ra, which is the separable area identified in the tissues constituting the dentition E. The separable area used to determine the observation direction here does not have to be the separable area designated as the display object, but may be an area adjacent to or near the separable area designated as the display object. When determining the observation direction for the root canal Ra, tooth T, jawbone Hj, etc. below, the observation direction is also determined based on the position information of the separable area of ​​the display object or near the display object.

[0132] This determines the detailed observation reference position Ps and the observation direction for the detailed observation image D. In step S9, the detailed observation image D is generated based on the detailed observation reference position Ps and the observation direction, and is displayed on the display device 22.

[0133] In this case, the cross section of the root canal Ra appears in the cross-sectional images Da and Dc along the root canal direction, making it easy to observe the living body from the root apex Rb to the root canal Ra.

[0134] If it is determined in step S21 that the target is a root canal Ra, the process proceeds to step S24 (see arrow Ar2 in FIG. 13).

[0135] In step S24, a reference position is identified based on a designated position for the root canal Ra in the dentition expansion image Ep and the three-dimensional position P1 of the root canal Ra.

[0136] For example, suppose that a root canal Ra is identified in the dentition expansion image Ep, and a position in the extension direction of the root canal Ra is specified. The position in the extension direction of the root canal Ra can be understood as a position in the up-down direction. Therefore, as shown in Fig. 15, the three-dimensional position of the detailed observation reference position Ps can be identified based on the correspondence relationship between the three-dimensional position P1 for the specified root canal Ra and the demarcable area corresponding position P2, and the specified upper and lower positions of the root canal Ra.

[0137] That is, when any root canal Ra is designated in the dentition expansion image Ep, the position in the buccolingual direction can be determined based on the three-dimensional position P1 of the root canal Ra.

[0138] Step S24 is an example of processing performed in accordance with a rule for determining the detailed observation reference position Ps based on position information of at least a part of the root canal Ra, which is a separable area.

[0139] In the next step S25, the observation direction is determined based on the specified direction of the root canal Ra and the dental arch. The determination of the observation direction based on the specified direction of the root canal Ra and the dental arch can be performed in the same manner as in step S23.

[0140] If it is determined in step S21 that the target is a tooth T, the process proceeds to step S26 (see arrow Ar3 in FIG. 13).

[0141] In step S26, a reference position is identified based on a designated position in the area of ​​the tooth T in the tooth row expanded image Ep and the shape of the tooth T.

[0142] For example, when a position in the region of tooth T is specified in the dentition exfoliated image Ep, the specified position is converted to a position in a three-dimensional coordinate system using a table that defines the correspondence between the three-dimensional position P1 of the demarcable region and the demarcable region-corresponding position P2, or by an inverse transformation process of the geometric transformation process that expands the dentition-constituting structures E onto the dentition exfoliated image Ep. However, since it is difficult to specify a position in the buccolingual direction when specifying a position for tooth T in the dentition exfoliated image Ep, the converted position in the three-dimensional coordinate system also lacks information regarding the buccolingual position. In other words, while the position of tooth T in the region of tooth T in the dentition exfoliated image Ep can be identified in the three-dimensional coordinate system in the tangential and vertical directions of the dental arch curve, it is not possible to identify the position in the buccolingual direction.

[0143] Therefore, the position in the buccal-lingual direction is identified based on the shape of the tooth T. For example, a line passing through a specified position in the three-dimensional coordinate system passes through the tooth T in the buccal-lingual direction. On this line, the center of the boundary of the tooth T is set as the buccal-lingual reference position at the detailed observation reference position Ps.

[0144] This allows the three-dimensional position of the detailed observation reference position Ps to be determined.

[0145] The buccal-lingual reference position at the detailed observation reference position Ps is not limited to the above position. For example, the buccal-lingual reference position at the detailed observation reference position Ps may be the position of the nearest root canal Ra or the position of the dental arch curve.

[0146] Step S26 is an example of processing performed according to a rule for determining the detailed observation reference position Ps based on position information of at least a part of the tooth T, which is a separable area.

[0147] In the next step S27, a reference root canal is identified to determine the observation direction. The reference root canal may be set to the root canal Ra of the tooth T to which the specified position belongs, or the root canal Ra closest to the specified position.

[0148] In the next step S28, the observation direction is determined based on the direction of the root canal Ra and the dental arch with reference to the reference root canal. The determination of the observation direction based on the specified direction of the root canal Ra and the dental arch can be performed in the same manner as in step S23.

[0149] The observation direction may be determined without being based on the direction of the root canal Ra. For example, as shown in Fig. 16, after step S26, step S28a may be executed instead of steps S27 and S28.

[0150] In step S28a, the observation direction is determined based on the dental arch curve, the horizontal direction, and the vertical direction. As shown in Fig. 17, the tangent direction Tc at the position on the dental arch curve Br closest to the detailed observation reference position Ps is calculated. In addition, the horizontal direction Ta and the vertical direction Tb perpendicular to the tangent direction Tc are calculated.

[0151] 18, the horizontal direction Ta, vertical direction Tb, and tangential direction Tc are defined as the observation directions of the cross-sectional images Da, Db, and Dc. The vertical direction is the direction of gravity, and the horizontal direction is the direction perpendicular to the direction of gravity.

[0152] The process of determining the observation direction of cross-sectional images Da, Db, and Dc that is not based on the direction of the root canal Ra may also be applied as a process for determining the observation direction for other root apex Rb, root canal Ra, jawbone Hj, areas outside the jawbone Hj, etc.

[0153] If it is determined in step S21 that the target is the jawbone Hj, the process proceeds to step S29 (see arrow Ar4 in FIG. 13).

[0154] In step S29, a reference position is identified based on a designated position in the region of the jawbone Hj in the dentition expansion image Ep and the shape of the jawbone Hj.

[0155] For example, when a position in the region of the jawbone Hj is specified in the dentition expansion image Ep, the specified position is converted to a position in a three-dimensional coordinate system using a table that defines the correspondence between the three-dimensional position P1 of the demarcable area and the demarcable area corresponding position P2, or by an inverse transformation process of the geometric transformation process that expands the dentition-constituting tissues E into the dentition expansion image Ep. However, as with the position specification for the tooth T, it is difficult to specify a position in the buccolingual direction when specifying a position for the jawbone Hj in the dentition expansion image Ep. Therefore, the position in the buccolingual direction is specified based on the shape of the jawbone Hj. As with the tooth T, the position in the buccolingual direction may be specified by using the center of the jawbone Hj in the buccolingual direction as the buccolingual reference position at the detailed observation reference position Ps.

[0156] This allows the three-dimensional coordinates of the detailed observation reference position Ps to be determined.

[0157] The reference position in the buccolingual direction at the detailed observation reference position Ps is not limited to the above position. For example, the reference position in the buccolingual direction at the detailed observation reference position Ps may be the position of the nearest root canal Ra or the position of the dental arch curve. Furthermore, for example, as shown in FIG. 19 , a horseshoe-shaped frame F that can encompass the jawbone Hj may be set for three-dimensional image data including the tissues constituting the dentition E. The horseshoe-shaped frame F is a frame that is preset to have a shape and size that can encompass a typical tissues constituting the dentition E. For example, the horseshoe-shaped frame F is set for the three-dimensional image data using an image registration algorithm or the like so that the tissues constituting the dentition E fit within the horseshoe-shaped frame F. Alternatively, the head holder 9 may be used to position the tissues constituting the dentition E of a standard build at a predetermined position in the three-dimensional image data, and the horseshoe-shaped frame F may be set at a position in the three-dimensional image data that can encompass the tissues constituting the dentition E. A line FL that passes through the center of the thickness direction of the horseshoe-shaped frame F may be preset, and a position on the line FL may be set as the position in the buccolingual direction. Of course, the line FL may be set closer to the buccal side or closer to the lingual side depending on the needs and desires of the user.

[0158] Step S29 is an example of processing performed according to a rule for determining the detailed observation reference position Ps based on position information of at least a part of the jawbone Hj, which is a separable area.

[0159] In the next step S30, a reference root canal is identified to determine the observation direction. The reference root canal may be set to the root canal Ra that is closest to the specified position.

[0160] In the next step S31, the observation direction is determined based on the direction of the root canal Ra and the dental arch with reference to the reference root canal. The determination of the observation direction based on the specified direction of the root canal Ra and the dental arch can be performed in the same manner as in step S23.

[0161] The observation direction may be determined based on the tangent direction of the curved line along which the jawbone Hj extends.

[0162] If it is determined in step S21 that the target is not the tooth T or the jawbone Hj, the process proceeds to step S32 (see arrow Ar5 in FIG. 13).

[0163] In step S32, a reference position is identified based on a designated position in the area outside the jawbone Hj of the dentition expansion image Ep and the horseshoe-shaped frame F.

[0164] For example, when a position of an area outside the jawbone Hj is specified in the dentition expansion image Ep, the specified position is converted into a position in a three-dimensional coordinate system by an inverse transformation process of the geometric transformation process that expands the dentition-constituting tissues E into the dentition expansion image Ep. As for the buccolingual direction, the position may be determined using the horseshoe-shaped frame F. Alternatively, the buccolingual center of the jawbone Hj closest to the specified position may be set as the buccolingual position.

[0165] This allows the three-dimensional coordinates of the detailed observation reference position Ps to be determined.

[0166] In the next step S33, a reference root canal is identified to determine the observation direction. The reference root canal may be set to the root canal Ra that is closest to the specified position.

[0167] In the next step S34, the observation direction is determined based on the direction of the root canal Ra and the dental arch with reference to the reference root canal. The determination of the observation direction based on the specified direction of the root canal Ra and the dental arch can be performed in the same manner as in step S23.

[0168] The observation direction may be determined based on the tangent direction of the curvature line of the jawbone Hj or the tangent direction of the dental arch curve that is closest to the specified position.

[0169] As described above, in determining the observation direction, a root canal that satisfies a predetermined condition for its positional relationship with the designated position, such as being closest to the designated position, can be set as the reference root canal, and the process of determining the observation direction may include a process of determining the observation direction based on the root canal direction in which the reference root canal extends. When a root apex is specified, the root canal connected to the root apex may be the reference root canal, and when a root canal is specified, the specified root canal itself may be the reference root canal.

[0170] That is, by specifying a position corresponding to the separable area in the dentition expanded image, an image for detailed observation of the separable area is generated from three-dimensional image data based on the correspondence between the position corresponding to the separable area and a three-dimensional position, and a reference position for detailed observation, which is a reference position for generating the image for detailed observation, is determined according to a predetermined rule. In this process, a process is performed to determine the observation direction of the image for detailed observation based on position information of at least a portion of the separable area identified in the tissues constituting the dentition, and the process of determining the observation direction may be a process in which a root canal that satisfies a positional relationship condition with the specified position of a specification operation via a user interface is used as a reference root canal and the observation direction is determined based on the root canal direction of the reference root canal.

[0171] In this way, the reference position Ps for detailed observation and the observation direction are determined for each type of object. After that, in step S9, an image D for detailed observation is generated based on the determined reference position Ps for detailed observation and the observation direction, and is displayed on the display device 22.

[0172] By setting the center in the buccal-lingual direction of the tooth T and jawbone Hj as the reference position Ps for detailed observation, the reference position Ps for detailed observation is set at a position within the anatomical region.

[0173] <Example of display processing for detailed observation images> An example of display processing for the detailed observation image D will be described below. Fig. 20 is a flowchart showing a specific example of processing in step S10 in Fig. 4.

[0174] When the detailed observation image D is displayed on the display device 22, the cross-sectional positions of the cross-sectional images Da, Db, and Dc of the detailed observation image D are changed in accordance with movement operations received through the user interfaces 24 and 26.

[0175] That is, after the image for detailed observation D is displayed, the process proceeds to step S50, processing related to an operation to adjust the image for detailed observation is started, and step S51 is processed. In step S51, the processing unit 30 determines whether or not a movement operation has been performed. The movement operation is accepted, for example, by an operation on an index Li via the user interfaces 24, 26. For example, as shown in FIG. 21, by moving any of the indexes Li (denoted as index Lia in FIG. 21) with a pointer device such as a mouse, the cross-sectional position indicated by the index Lia is moved. In this way, the movement operation is accepted. The movement operation may also be performed with a switch device such as a keyboard.

[0176] The movement operation in step S51 may be an operation to change the tilt of the index Li. For example, when a central region of the index Li is dragged with a pointer device such as a mouse, the position of the index Li may be changed, and when an end region of the index Li is dragged with a pointer device such as a mouse, the tilt of the index Li may be changed. A rotation operation of the three-dimensional image may be performed by adding a pointing operation to a location outside the index Li of the cross-sectional image Da, the cross-sectional image Db, or the cross-sectional image Dc. Depending on the direction and amount of the dragging operation, the tilt of the index Li is changed, and a movement operation to tilt the cross-sectional position is accepted.

[0177] If it is determined in step S51 that no movement operation has been performed, the process proceeds to step S54, and if it is determined that a movement operation has been performed, the process proceeds to step S52.

[0178] In step S52, coordinates and orientation corresponding to the movement operation are calculated. The coordinates corresponding to the movement operation are coordinates obtained by shifting the coordinates of the three-dimensional position P1 before the movement by the amount of movement corresponding to the movement operation. The coordinates after the movement operation are converted using the same process as the conversion from the three-dimensional position P1 to the demarcable area corresponding position P2, thereby calculating the coordinates of the demarcable area in the dentition unfolded image Ep after the movement operation. In addition, the orientation corresponding to the movement operation is an orientation obtained by tilting the direction perpendicular to any of the cross-sectional images Da, Db, Dc at the three-dimensional position P1 before the movement by the amount of tilt corresponding to the movement operation.

[0179] Step S53 may be inserted after step S52. In step S53, the processing unit 30 changes the position of the image indicating the specified position in the dentition unfolded image Ep to the position after the movement operation. Furthermore, cross-sectional images Da, Db, and Dc are generated and displayed based on the coordinates and orientation after the movement operation. After the movement operation, the cross-sectional images Da, Db, and Dc are generated so that the coordinates after the movement operation are positioned at the center. Therefore, in the cross-sectional images Da, Db, and Dc, the image before the operation may be shifted to the opposite side of the movement operation direction, or an image toward the depth or front of the image before the operation may be displayed (see the outline indicated by the two-dot chain line in FIG. 13). The processing of step S53 may be configured to be optionally executable, allowing the user to select whether to proceed to step S53 through the user interface 24, 26. In this case, step S53 may be skipped. Alternatively, step S53 itself may be omitted.

[0180] When step S53 is completed, the process proceeds to step S54 (when the process of step S53 is omitted, the process proceeds to step S54 when step S52 is completed).

[0181] In step S54, it is determined whether or not there is a signal to end the display of the image for detailed observation D. The signal to end the display is transmitted, for example, when the user issues an instruction to end the display via the user interfaces 24, 26. If there is a signal to end the display, the display of the image for detailed observation D ends. If there is no signal to end the display, the process returns to step S51.

[0182] <Effects, etc.> According to the image processing device 20, image processing method, and program 34a configured as described above, by specifying the demarcable area corresponding position P2 in the dentition expansion image Ep, a detailed observation reference position Ps for the demarcable area corresponding position P2 is generated based on the correspondence between the demarcable area corresponding position P2 and the three-dimensional position P1, and is displayed on the display device 22. At this time, the detailed observation reference position Ps, which is the reference position for generating the detailed observation image D, is determined according to a predetermined rule. Therefore, the position of the detailed observation image D can be appropriately set in the dentition expansion image Ep. For example, even if it is difficult to specify the detailed observation reference position Ps in the buccolingual direction in the dentition expansion image Ep, the detailed observation reference position Ps specified in the buccolingual direction can also be appropriately set.

[0183] Furthermore, since the above rule is a rule for determining the detailed observation reference position Ps based on position information of at least a part of the demarcable area, the detailed observation reference position Ps is determined according to the position of the demarcable area.

[0184] Furthermore, a detailed observation image D that is easy to observe in detail can be generated by determining the observation direction of the detailed observation image D based on position information of at least a part of the separable area identified in the tissues constituting the dentition E. For example, by generating a detailed observation image D that follows the direction of the root canal Ra based on position information of the root canal Ra as a separable area, the root canal Ra can be easily observed in detail.

[0185] Furthermore, it is difficult to set the position in the buccal-lingual direction in the dentition expansion image Ep. Therefore, the buccal-lingual detailed observation reference position Ps is determined according to a predetermined rule. This makes it possible to appropriately set the position of the detailed observation image D in the buccal-lingual direction.

[0186] Furthermore, the type of demarcable area is identified, and rules are established for each type. This makes it possible to set a reference position Ps for detailed observation that is appropriate for each type. For example, if the demarcable area is the root apex Rb, the reference position Ps for detailed observation can be set at the position of the root apex Rb itself; if the demarcable area is the root canal Ra, the reference position Ps for detailed observation can be set at a position along the root canal Ra. Furthermore, if the demarcable area is a tooth T, the reference position Ps for detailed observation can be set at the center of the tooth T in the buccolingual direction.

[0187] Furthermore, for example, if the demarcable area is a lesion area, setting the center of the lesion area as the detailed observation reference position Ps makes it easier to observe the areas extending from the center of the lesion area. The center may be, for example, the geometric center or the center of gravity.

[0188] Furthermore, by setting anatomical distinct regions such as the tooth T, root canal Ra, root apex Rb, and jawbone Hj as the demarcable regions, the position of the detailed observation image D relative to the anatomical distinct regions can be set appropriately.

[0189] Furthermore, by setting the central position in the buccal-lingual direction of the tooth T or the jawbone Hj as the reference position Ps for detailed observation, the internal structure of the anatomical region can be observed using the image D for detailed observation.

[0190] Furthermore, if the detailed observation image D includes three cross-sectional images Da, Db, and Dc that are orthogonal to one another, it is easy to observe the demarcable area in detail.

[0191] The rule may also determine the observation directions of the cross-sectional images Da, Db, and Dc according to the type of separable area. For example, as described above, the observation directions for the root apex Rb and root canal Ra may be determined with reference to the root canal Ra, and the observation directions for the tooth T and jawbone Hj may be determined with reference to the horizontal and vertical directions without reference to the root canal Ra (see FIG. 18).

[0192] This allows the direction of the cross-sectional image to be set according to the type of separable area.

[0193] In addition, by identifying multiple dividable areas, displaying a tooth row expanded image Ep on the display device 22 in which the multiple dividable areas are displayed at positions corresponding to the dividable areas, accepting specification of a portion of the multiple dividable areas through the user interfaces 24, 26, and displaying an image D for detailed observation corresponding to the accepted portion of the dividable areas on the display device 22, it is possible to observe in detail the image for detailed observation corresponding to the specified portion of the dividable areas from the multiple dividable areas.

[0194] Furthermore, by changing the reference position Ps for detailed observation in response to a reference position change operation via the user interfaces 24 and 26, it is easy to observe the separable area at various positions.

[0195] In this embodiment, the reference position for detailed observation Ps can be changed by successive position designation operations on the row-of-teeth expanded image Ep, or by operations on the image for detailed observation D.

[0196] {Variation} Various modifications will be described based on the above embodiment.

[0197] In the above embodiment, the demarcable area is mainly an anatomical demarcable area. As shown in Fig. 22, the demarcable area may be a biologically distinctive area, for example, a lesion area Ld.

[0198] The lesion area Ld may be identified by applying a trained machine learning model similar to that used to identify the tissues that make up the dentition. For example, a large amount of data in which lesion areas are mapped onto 3D volume data is prepared as training data. Using this training data, a machine learning model is prepared that is trained to segment the lesion area in the 3D volume data. The trained machine learning model is applied to the 3D volume data to identify the lesion area in a 3D coordinate system.

[0199] The lesion area in the three-dimensional volume data may be identified by image extraction processing, for example, pattern matching processing.

[0200] The detection of the lesion area does not have to be performed based on the three-dimensional volume data. For example, the lesion area may be identified by applying a machine learning model or pattern matching based on slice data obtained by slicing the three-dimensional volume data in any direction.

[0201] The lesion area Ld may not be displayed as a clearly distinguishable image in the dentition expansion image Ep. Therefore, for the lesion area Ld, annotation images Qa and Qb may be displayed at the position P2 corresponding to the separable area in the dentition expansion image Ep.

[0202] The annotation images Qa and Qb are images that indicate the separable area. The annotation images Qa and Qb may be images that exhibit a color, shape, or change that is distinguishable from the background dentition expansion image Ep. For example, the annotation images Qa and Qb may be images that exhibit a color different from that of the dentition expansion image Ep. More specifically, the annotation images Qa and Qb may be images that exhibit a conspicuous warm color, such as red, orange, or yellow. The annotation images Qa and Qb may be images that undergo a display change, such as blinking, a color change, or a shape change, that distinguishes them from the dentition expansion image Ep. The annotation images Qa and Qb may be shapes that distinguish them from the dentition expansion image Ep, such as a circle, a regular polygon, a radial shape, a cross shape, or an exclamation mark shape.

[0203] The annotation images Qa and Qb may have a shape that shows the outline of the lesion area Ld. In this case, the approximate shape and size of the lesion area Ld can be known by looking at the annotation images Qa and Qb.

[0204] When a plurality of demarcable areas are detected, the annotation images Qa and Qb are displayed so as to be recognizable in correspondence with each of the plurality of demarcable areas.

[0205] Note that the case where multiple annotation images Qa, Qb are displayed in a recognizable manner includes not only the case where multiple annotation images Qa, Qb are displayed simultaneously, but also the case where multiple annotation images Qa, Qb are displayed sequentially so that the presence of multiple annotation images Qa, Qb can be recognized. For example, multiple annotation images Qa, Qb may be displayed sequentially within 5 seconds, 3 seconds, or 1 second.

[0206] When multiple annotation images Qa, Qb exist, one of the multiple annotation images Qa, Qb is designated, and the detailed observation image D corresponding to the designated image Qa, Qb is displayed. The designated annotation image Qb may be displayed so as to be distinguished from the other annotation images Qa. In Fig. 22, the designated annotation image Qb is displayed with a double circle, and the other annotation images Qa are displayed with single circles.

[0207] The image in which annotation images Qa and Qb are superimposed on the tooth row extruded image Ep is the separable area arrangement extruded image Eq.

[0208] For a demarcable area such as the lesion area Ld, the center of the demarcable area may be set as the detailed observation reference position Ps. The center may be the center of the area identified as the demarcable area, for example, the geometric center or the center of gravity.

[0209] According to this modification, the position of the detailed observation image D relative to the separable area can be appropriately set.

[0210] Furthermore, by displaying the annotation images Qa and Qb so as to indicate the demarcable areas, it is easy to recognize the demarcable areas such as the lesion area Ld using the annotation images Qa and Qb as clues.

[0211] Furthermore, by setting the center of a demarcable area such as the lesion area Ld as the detailed observation reference position Ps, observation can be performed using the detailed observation image D with the center of the demarcable area as the reference.

[0212] In the row of teeth expanded image Ep, the separable areas may be displayed in different ways depending on their types. For example, the teeth T and the jawbone Hj may be displayed in different colors.

[0213] In the above embodiment, an example has been described in which each position of the structures E constituting the dentition is identified based on three-dimensional volume data, and the identified structures E constituting the dentition are developed into an expanded image Ep of the dentition.

[0214] However, instead of individually identifying the positions of the tissues E that constitute the dentition based on the three-dimensional volume data, the dentition may be expanded into an expanded image Ep of the dentition based on a standard region of the tissues E that constitute the dentition.

[0215] For example, as shown in Fig. 23, when performing CT imaging with the CT imaging device 10, the head H is positioned at a fixed position by the head holder 9. As a result, the dentition-forming tissues E are also positioned at a fixed position relative to the head holder 9, as shown in Fig. 24.

[0216] The positional relationship between the head holder 9 and the X-ray generator 11 and X-ray detector 12 can be a known positional relationship. Furthermore, the area in the head H where the tissues constituting the dentition E extend can be considered to be more or less constant. For this reason, in the three-dimensional volume data based on CT imaging data, the area of ​​the standard tissues constituting the dentition E can be treated as the area of ​​the actual tissues constituting the dentition E.

[0217] Furthermore, assuming a standard tissue E constituting the dentition, a general-purpose conversion process can be determined in advance to convert the standard tissue E constituting the dentition into a dentition expanded image Ep. The region of the three-dimensional volume data where the tissue E constituting the dentition can be expected to exist can be converted into a dentition expanded image Ep by the general-purpose conversion process. Furthermore, by performing the general-purpose conversion process on the identified separable region of the three-dimensional volume data, the corresponding position of the separable region in the dentition expanded image Ep can be calculated.

[0218] In the above embodiment, the case where the image processing device 20 is used in combination with the CT imaging device 10 has been described.

[0219] The image processing device 20 can also be configured as a device separate from the CT imaging device 10.

[0220] In this case, like the image processing device 120 shown in Figures 25 and 26, the image processing device 120 may include a data access device 130 that is connected by turning the connection port 36. The data access device 130 is, for example, a device that can read data recorded on a recording medium 128. The recording medium 128 may be an optical recording medium such as an optical disc, or may be a flash memory such as a USB memory or an SD card. The data access device 130 may be an optical disc reader or a card reader.

[0221] Image data obtained by CT imaging is recorded on the recording medium 128. The image data may be a group of X-ray projection image data, three-dimensional volume data, or a data group of multiple tomographic images.

[0222] The image processing device 120 can execute the same processing as in the above embodiment by reading image data obtained by CT imaging via the data access device 130.

[0223] Image data obtained by CT scanning may be stored in a server device, and the image processing device 120 may access the server device via a communication network to obtain the image data obtained by CT scanning. In this case, the server device may be located within the facility where the image processing device 120 is located, or may be located outside the facility. The server device may also be a cloud server. The image processing device 120 can access the server device via a dedicated line or a public line network to obtain the image data obtained by CT scanning.

[0224] {Other variations} In the above embodiment and various modified examples, other information may be displayed around the dentition expansion image Ep or the detailed observation image D. For example, the name of a disease may be written. For example, if multiple lesion areas Ld are detected, the disease names of the multiple lesion areas may be displayed. The disease names may be displayed together with the cross-sectional images.

[0225] The configurations described in the above embodiment and modifications can be combined as appropriate as long as they are not mutually contradictory.

[0226] The present disclosure discloses the following aspects.

[0227] The first aspect is an image processing device that processes image data obtained by CT imaging of tissues that constitute the dentition to generate an image for diagnosis, and is equipped with a storage device that stores the image data, a processing device, and a display device that displays an image for observation based on the output of the processing device, and the processing device generates three-dimensional image data of the tissues that constitute the dentition based on the image data, identifies a demarcable area in the tissues that constitute the dentition based on the image data, identifies a three-dimensional position where the demarcable area exists in a coordinate system of the three-dimensional image, and generates an expanded image of the dentition in which the tissues that constitute the dentition are expanded based on the three-dimensional image data. and specifies a position in the dental arch expanded image corresponding to the demarcable area that corresponds to the three-dimensional position, displays the dental arch expanded image in which the demarcable area is displayed at the position corresponding to the demarcable area on the display device, generates an image for detailed observation of the demarcable area from the three-dimensional image data by specifying the position corresponding to the demarcable area in the dental arch expanded image based on the correspondence between the position corresponding to the demarcable area and the three-dimensional position, determines a reference position for detailed observation that is a reference position for generating the image for detailed observation according to a predetermined rule, and displays the image for detailed observation on the display device.

[0228] According to this image processing device, by specifying a position corresponding to the demarcable area in the dentition expansion image, a reference position for detailed observation of the position corresponding to the demarcable area is generated based on the correspondence between the position corresponding to the demarcable area and a three-dimensional position, and is displayed on the display device. At this time, the reference position for detailed observation, which is the reference position for generating the image for detailed observation, is determined according to a predetermined rule. Therefore, the position of the image for detailed observation can be appropriately set in the dentition expansion image.

[0229] The processing device may set a dentition-forming tissue region, which is the region in which the dentition-forming tissues extend, and a dentition-formed region obtained by expanding the dentition-forming tissue region, and may expand the dentition-formed tissues by expanding image data of the dentition-forming tissues in the dentition-forming tissue region so as to fit the shape of the dentition-formed region. This allows for appropriate image data processing for visual recognition of the separable region.

[0230] The unfolding process may be performed so that the buccal-lingual direction in the curved state before unfolding, which is the state of the tissue region constituting the dentition before unfolding, corresponds to the normal viewing direction in the view state after unfolding, which is the state of the unfolded dentition region after unfolding. This makes it easy to understand the position of the separable area.

[0231] The dentition-constituting tissue region may be set to have a thickness in the buccolingual direction, and the dentition-expanded region may be set to have a thickness in the normal viewing direction corresponding to the buccolingual direction. This makes it possible to recognize a separable region within an appropriate range.

[0232] In the expansion, an original coordinate calculation may be performed to associate the decomposable area with the three-dimensional position of the decomposable area corresponding position. In the original coordinate calculation, a calculation may be performed to identify the position of the three-dimensional position of the decomposable area in the buccolingual direction, and to identify the position of the decomposable area corresponding position in the normal viewing direction corresponding to the buccolingual direction. This makes it possible to accurately calculate the three-dimensional position of the decomposable area and the decomposable area corresponding position.

[0233] A second aspect is the image processing device according to the first aspect, wherein the rule is a rule for determining the detailed observation reference position based on position information of at least a part of the demarcable area.

[0234] This allows the detailed observation reference position to be determined based on the position information of at least a portion of the separable area.

[0235] A third aspect is an image processing device according to the first or second aspect, wherein the processing device determines the observation direction of the detailed observation image based on positional information of at least a portion of the distinguishable area identified in the dentition-forming tissue.

[0236] In this case, the observation direction of the detailed observation image can be determined based on the position information of at least a part of the separable area or an area adjacent to the separable area, making detailed observation easy.

[0237] A fourth aspect is the image processing device according to any one of the first to third aspects, wherein the detailed observation reference position includes a position in the buccal-lingual direction.

[0238] It is difficult to set the position in the buccal-lingual direction in a dental arch expansion image. Therefore, the reference position for detailed observation in the buccal-lingual direction is determined according to a predetermined rule. This makes it possible to appropriately set the position of the detailed observation image in the buccal-lingual direction.

[0239] A fifth aspect is an image processing device according to any one of the first to fourth aspects, wherein the processing device identifies a type of the distinguishable area, and the rules are set in advance for each type.

[0240] This allows the reference position for detailed observation to be set appropriately for each type.

[0241] A sixth aspect is an image processing device according to any one of the first to fifth aspects, wherein the processing device detects a biological characteristic area in the tissues that constitute the dentition based on the image data and sets the biological characteristic area as the divisible area.

[0242] This allows the position of the detailed observation image to be appropriately set relative to the biological feature region.

[0243] A seventh aspect is an image processing device according to the sixth aspect, wherein the processing device displays on the display device a biometric feature area arrangement expanded image in which the annotation image indicating the biometric feature area is superimposed on the dentition expanded image so that the annotation image is positioned at a position corresponding to the separable area.

[0244] This makes it easier to recognize biometric feature regions using the annotation image as a clue.

[0245] An eighth aspect is the image processing device according to the sixth or seventh aspect, wherein the processing device sets the center of the biometric characteristic area as the detailed observation reference position.

[0246] This allows observation using the detailed observation image with the center of the biological characteristic area as a reference.

[0247] A ninth aspect is an image processing device according to any one of the first to eighth aspects, wherein the processing device detects an anatomical distinction area that anatomically distinguishes the tissues that constitute the dental arch based on the image data, and sets the anatomical distinction area as the divisible area.

[0248] This allows the position of the detailed observation image to be appropriately set relative to the anatomical region.

[0249] A tenth aspect is the image processing device according to the ninth aspect, wherein the processing device sets a position within the anatomical division as the detailed observation reference position.

[0250] This allows the internal structure of the anatomical region to be observed using the detailed observation image.

[0251] The processing device may perform processing to distinguish the dentition region from the alveolar bone region based on the three-dimensional image data, and perform image processing to display the dentition region and the alveolar bone region in different modes in the dentition expansion image. This allows the dentition region and the alveolar bone region to be displayed separately in the dentition expansion image, making it easier to grasp the position of the separable region.

[0252] The processing device may use different colors for the dentition region and the alveolar bone region in the dentition expansion image, thereby making it easier to distinguish and recognize the dentition region and the alveolar bone region.

[0253] The processing device may set a transparency for the alveolar bone region that allows the dentition region to be seen through, thereby enabling observation of the separable region for the portion of the dentition that is inside the alveolar bone while grasping the positional relationship between the alveolar bone and the dentition.

[0254] The processing device may be configured to display the functional tissues that make up the dentition of a living body by a boundary surface between presence and absence, and to perform gaze direction-responsive transparency image processing, which is image processing in which the transparency of the boundary surface changes depending on the gaze direction, thereby making it easier to visually recognize the shapes of the functional tissues that make up the dentition.

[0255] When the element that increases transparency is a parent transparency element, and increasing transparency is parent transparency, and the element that decreases transparency is an anti-transparency element, and decreasing transparency is anti-transparency, the gaze direction-compatible transparency image processing may be a combination of at least one of the following group A and at least one of the following group B. Group A: Processing to enlarge or increase the parent transparency element of the boundary surface of normal vision Processing to promote parent transparency of the boundary surface of normal vision Treatment to reduce, diminish or eliminate the anti-transparency elements of the interface of normal vision Treatment to suppress the anti-transparency of the boundary surface of normal vision Group B: Processing to reduce, decrease or eliminate the parent transparency elements of the boundary surface in oblique or side views - Processing to suppress parent transparency of the boundary surface in oblique or side view Treatment to enlarge or increase the anti-transparency factor of the said boundary surface in oblique or lateral view Treatment to promote anti-transparency of the boundary surface in oblique or lateral views This makes it easier to visually recognize the three-dimensional shapes of the functional structures that constitute the dentition.

[0256] An eleventh aspect is the image processing device according to any one of the first to tenth aspects, wherein the detailed observation image includes three cross-sectional images that are orthogonal to each other.

[0257] In this case, since the detailed observation image includes three cross-sectional images that are orthogonal to each other, it is easy to observe the demarcable area in detail.

[0258] A twelfth aspect is an image processing device according to the eleventh aspect, wherein the processing device identifies a type of the divisible area, and the rule determines the direction of the three cross-sectional images passing through the reference position for detailed observation according to the type.

[0259] This allows the direction of the cross-sectional image to be set for each type.

[0260] A thirteenth aspect is an image processing device according to any one of the first to twelfth aspects, further comprising a user interface, wherein the processing device identifies a plurality of the divisible areas, displays the tooth row expanded image on the display device in which the plurality of divisible areas are displayed at positions corresponding to the divisible areas, accepts designation of a portion of the plurality of divisible areas through the user interface, and displays the detailed observation image corresponding to the accepted portion of the divisible area on the display device.

[0261] This allows detailed observation of the detailed observation image corresponding to a specified part of the plurality of separable areas.

[0262] A fourteenth aspect is an image processing device according to any one of the first to thirteenth aspects, further comprising a user interface, wherein the processing device changes the reference position for detailed observation in response to a reference position change operation performed through the user interface.

[0263] This makes it easy to observe the separable area at various positions by changing the reference position of the detailed observation image.

[0264] The fifteenth aspect is an image processing method for generating an image for diagnosis by processing image data obtained by CT scanning of tissues forming the dental arch, the image processing method comprising the steps of: generating three-dimensional image data of the tissues forming the dental arch based on the image data; identifying a separable area in the tissues forming the dental arch based on the image data; identifying a three-dimensional position where the separable area exists in the coordinate system of the three-dimensional image; generating an expanded dental image in which the tissues forming the dental arch are expanded based on the three-dimensional image data; identifying a separable area corresponding position in the expanded dental image that corresponds to the three-dimensional position; displaying the expanded dental image in which the separable area is displayed at the separable area corresponding position; generating a detailed observation image of the separable area from the three-dimensional image data based on the correspondence between the separable area corresponding position and the three-dimensional position by specifying the separable area corresponding position in the expanded dental image;

[0265] According to this image processing method, the position of the detailed observation image can be appropriately set in the dentition expansion image.

[0266] The sixteenth aspect is a program for generating diagnostic images by processing image data obtained by CT scanning of tissues forming the dental row, the program causing a computer to execute the following processes: generate three-dimensional image data of the tissues forming the dental row based on the image data; identify a separable area in the tissues forming the dental row based on the image data; identify a three-dimensional position where the separable area exists in the coordinate system of the three-dimensional image; generate an expanded image of the dental row in which the tissues forming the dental row are expanded based on the three-dimensional image data; identify a position in the expanded image of the dental row corresponding to the separable area that corresponds to the three-dimensional position; display the expanded image of the dental row in which the separable area is displayed at the position corresponding to the separable area; generate a detailed observation image of the separable area from the three-dimensional image data based on the correspondence between the position corresponding to the separable area and the three-dimensional position by specifying the position corresponding to the separable area in the expanded image of the dental row; determine a detailed observation reference position, which is a reference position for generating the image for detailed observation, in accordance with predetermined rules; and display the image for detailed observation.

[0267] According to this program, the position of the detailed observation image can be appropriately set in the dentition expansion image.

[0268] Although the present invention has been described in detail as above, the above description is merely illustrative in all respects and does not limit the present invention. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present invention. [Explanation of symbols]

[0269] 10 CT imaging device 20, 120 Image processing device 22 Display device 24, 26 User Interface 30 processing units 32 Arithmetic circuit 32a processor 34 Storage device 34a Program 34b Data D. Detailed observation image Da, Db, Dc cross-sectional images E. Tissues that make up the dentition Ep dental arch expansion image Hj jawbone Ht dental arch L partitionable area Ld lesion area Ps Reference position for detailed observation P1 3D position P2 Position corresponding to the divisible area Qa and Qb annotation images Ra root canal Rb root apex T tooth

Claims

1. An image processing device that processes image data obtained by CT imaging of tissues constituting the dentition to generate an image for diagnosis, a storage device that stores the image data; a processing device; a display device that displays an image for observation based on the output of the processing device; Equipped with The processing device includes: generating three-dimensional image data of the tissues constituting the dentition based on the image data; Identifying a separable area in the tissues constituting the dentition based on the image data; identifying a three-dimensional position where the separable area exists in a coordinate system of the three-dimensional image; generating a dental arch expanded image in which the dental arch constituent tissues are expanded based on the three-dimensional image data; identifying a demarcable area corresponding position in the dental arch expansion image that corresponds to the three-dimensional position; displaying the dental arch expanded image in which the demarcable area is displayed at a position corresponding to the demarcable area on the display device; generating a detailed observation image of the demarcable area from the three-dimensional image data based on a correspondence relationship between the demarcable area corresponding position and the three-dimensional position by specifying the demarcable area corresponding position in the dentition development image; determining a detailed observation reference position, which is a reference position for generating the detailed observation image, in accordance with a predetermined rule; an image processing device that displays the detailed observation image on the display device;

2. 2. The image processing device according to claim 1, The rule is a rule for determining the detailed observation reference position based on position information of at least a part of the separable area.

3. 3. The image processing device according to claim 1, The image processing device determines an observation direction of the detailed observation image based on position information of at least a part of the demarcable area identified in the tissues that constitute the dentition.

4. 3. The image processing device according to claim 1, An image processing device, wherein the detailed observation reference position includes a position in the buccal-lingual direction.

5. 3. The image processing device according to claim 1, The processing device includes: Identifying the type of the separable area, The image processing device, wherein the rules are set in advance for each type.

6. 3. The image processing device according to claim 1, The processing device includes: detecting a biological characteristic area in the tissues constituting the dentition based on the image data; An image processing device that sets the biometric feature region as the separable region.

7. 7. The image processing device according to claim 6, The processing device is an image processing device that displays, on the display device, a biometric feature area arrangement expansion image in which the annotation image indicating the biometric feature area is superimposed on the dentition expansion image so that the annotation image is positioned at a position corresponding to the separable area.

8. 7. The image processing device according to claim 6, The processing device includes: an image processing device that sets the center of the biometric feature area as the reference position for detailed observation;

9. 3. The image processing device according to claim 1, The processing device includes: Detecting anatomical regions in which the tissues constituting the dentition are anatomically separated based on the image data; an image processing device that sets the anatomical distinct region as the separable region;

10. 10. The image processing device according to claim 9, The processing device includes: an image processing device that sets a position within the anatomical region as the reference position for detailed observation;

11. 3. The image processing device according to claim 1, An image processing device, wherein the detailed observation image includes three cross-sectional images that are orthogonal to each other.

12. The image processing device according to claim 11, The processing device includes: Identifying the type of the separable area, The rule determines the directions of the three cross-sectional images that pass through the detailed observation reference position for each type.

13. 3. The image processing device according to claim 1, further comprising a user interface; The processing device includes: Identifying a plurality of the separable regions; displaying, on the display device, the dental arch expanded image in which the plurality of demarcable areas are displayed at positions corresponding to the demarcable areas; Accepting designation of a portion of the plurality of separable areas through the user interface; an image processing device that displays the image for detailed observation corresponding to the received part of the separable area on the display device;

14. 3. The image processing device according to claim 1, further comprising a user interface; The processing device includes: an image processing device that changes the reference position for detailed observation in response to a reference position change operation performed through the user interface;

15. An image processing method for generating a diagnostic image by processing image data obtained by CT imaging of tissues constituting a dental arch, comprising: generating three-dimensional image data of the tissues constituting the dentition based on the image data; Identifying a separable area in the tissues constituting the dentition based on the image data; identifying a three-dimensional position where the separable area exists in a coordinate system of the three-dimensional image; generating a dental arch expanded image in which the dental arch constituent tissues are expanded based on the three-dimensional image data; identifying a demarcable area corresponding position in the dental arch expansion image that corresponds to the three-dimensional position; displaying the dental arch expanded image in which the demarcable area is displayed at a position corresponding to the demarcable area; generating a detailed observation image of the demarcable area from the three-dimensional image data based on a correspondence relationship between the demarcable area corresponding position and the three-dimensional position by specifying the demarcable area corresponding position in the dentition development image; determining a detailed observation reference position, which is a reference position for generating the detailed observation image, in accordance with a predetermined rule; and displaying the detailed observation image.

16. A program for generating diagnostic images by processing image data obtained by CT imaging of tissues constituting the dental arch, On the computer, generating three-dimensional image data of the tissues constituting the dentition based on the image data; Identifying a separable area in the tissues constituting the dentition based on the image data; identifying a three-dimensional position where the separable area exists in a coordinate system of the three-dimensional image; generating a dental arch expanded image in which the dental arch constituent tissues are expanded based on the three-dimensional image data; identifying a demarcable area corresponding position in the dental arch expansion image that corresponds to the three-dimensional position; displaying the dental arch expanded image in which the demarcable area is displayed at a position corresponding to the demarcable area; generating a detailed observation image of the demarcable area from the three-dimensional image data based on a correspondence relationship between the demarcable area corresponding position and the three-dimensional position by specifying the demarcable area corresponding position in the dentition development image; determining a detailed observation reference position, which is a reference position for generating the detailed observation image, in accordance with a predetermined rule; A program that causes a process of displaying the detailed observation image to be executed.

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