Image processing device and image processing program

Abstract

To provide a stereoscopic image for display suitable for the observation in a wider range on the basis of image data on a maxillofacial region acquired by X-ray CT imaging.SOLUTION: An image processing device for performing processing of image data on a maxillofacial region obtained by X-ray CT imaging, includes: a storage unit for storing image data including an alveolus bone region; and an image processing unit for generating a stereoscopic image for display on the basis of the image data. The image processing unit executes processing for setting a continuous cross section curved along the alveolus bone region in the alveolus bone region (step S4), and processing for generating an image, as the stereoscopic image for display, displayed so that a transparency degree in a first region positioned in one side region with the continuous cross section as a boundary of the alveolus bone region is larger than a transparency degree in a second region positioned in the other side region with the continuous cross section as a boundary of the alveolus bone region (steps S5 and S6).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a technique for processing image data of the maxillofacial region obtained by X-ray CT imaging. [Background technology]

[0002] Patent Document 1 discloses displaying a volume rendering image based on reconstruction data of a three-dimensional region obtained by X-ray CT imaging. It also discloses that when generating a volume rendering image for display, the volume rendering image includes any of tomographic images of an X-, Y-, or Z-plane in an XYZ coordinate system that pass through a point of interest in the three-dimensional region and are orthogonal to each other.

[0003] Techniques relating to the display of CT images are also disclosed in Patent Documents 2 and 3. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-305203 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-259822 [Patent Document 3] Japanese Patent Application Publication No. 8-215192 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a volume rendering image of the maxillofacial region, it is difficult to grasp the internal structure of the volume rendering image, such as the state of the alveolar bone and the state of the teeth, in three dimensions. Furthermore, the jawbone is curved, and multiple teeth are arranged in a curved, arched shape. Therefore, even if a volume rendering image includes any of the cross-sectional images of the X-, Y-, and Z-planes, the region suitable for observation is limited.

[0006] Therefore, an object of the present disclosure is to provide a stereoscopic image for display that is suitable for observation over a wider range, based on image data of the maxillofacial region obtained by X-ray CT imaging. [Means for solving the problem]

[0007] The image processing device of the present disclosure is an image processing device that processes image data of the maxillofacial region obtained by X-ray CT imaging, and is equipped with a memory unit that stores the image data including the alveolar bone region, and an image processing unit that generates a three-dimensional image for display based on the image data, wherein the image processing unit performs the following processes: setting successive cross sections in the alveolar bone region that curve along the alveolar bone region; and generating, as the three-dimensional image for display, an image in which the transparency of a first region located within one side of the alveolar bone region with the successive cross sections as a boundary is displayed greater than the transparency of a second region located within the alveolar bone region with the successive cross sections as a boundary.

[0008] In addition, the image processing program of the present disclosure is an image processing program for causing a computer that processes image data of the maxillofacial region obtained by X-ray CT imaging to execute the following processes: setting continuous cross sections that curve along the alveolar bone region in the alveolar bone region included in the image data; and generating a three-dimensional image for display in which the transparency of a first region located within one side of the alveolar bone region with the continuous cross sections as a boundary is displayed greater than the transparency of a second region located within the alveolar bone region with the continuous cross sections as a boundary. [Effects of the Invention]

[0009] According to the present disclosure, a stereoscopic image for display suitable for observation over a wider range can be provided based on image data of the maxillofacial region obtained by X-ray CT imaging. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic front view showing an X-ray imaging apparatus according to an embodiment. [Figure 2]FIG. 2 is an explanatory diagram showing a state in which the subject support section supports the head. [Figure 3] FIG. 3 is an explanatory diagram showing the positional relationship between the subject support part and the dental arch region. [Figure 4] FIG. 4 is a block diagram showing an example of the electrical configuration of the image processing device. [Figure 5] FIG. 5 is an explanatory diagram for explaining the characteristics of a stereoscopic image when viewed stereoscopically. [Figure 6] FIG. 6 is a flowchart showing an example of processing by the image processing device. [Figure 7] FIG. 7 is an explanatory diagram showing an example of setting continuous cross sections for the alveolar bone region. [Figure 8] FIG. 8 is a diagram showing an example of a continuous cross section. [Figure 9] FIG. 9 is an explanatory diagram showing an example of setting transparency for the alveolar bone region. [Figure 10] FIG. 10 is a diagram showing a display example of a stereoscopic image for display. [Figure 11] FIG. 11 is an enlarged view of FIG. [Figure 12] FIG. 12 is a diagram showing a display example according to a comparative example. [Figure 13] FIG. 13 shows a state in which a tooth is embedded in the alveolar bone. [Figure 14] FIG. 14 shows a continuous cross section curved along the alveolar bone region of the maxilla. [Figure 15] FIG. 15 is an explanatory diagram showing an example of processing for identifying the surface of the alveolar bone region. [Figure 16] FIG. 16 is a diagram showing an example of setting continuous cross sections based on the surface of the alveolar bone region. [Figure 17] FIG. 17 shows an example in which the continuous cross section is translated forward. [Figure 18] FIG. 18 shows an example in which the continuous cross sections are moved in the buccolingual direction. [Figure 19] FIG. 19 is a diagram showing another example in which the continuous cross sections are moved in the buccolingual direction. [Figure 20] FIG. 20 shows an example in which the continuous cross sections are partially moved in the buccolingual direction. [Figure 21] FIG. 21 is an explanatory diagram showing an example of setting display colors. [Figure 22] FIG. 22 is a diagram showing a display example when the display colors in the second region are color-coded according to the positions in the buccolingual direction. [Figure 23] FIG. 23 is a diagram showing a volume rendering image in which the transparency of the first region is set to an intermediate value. [Figure 24] FIG. 24 is a diagram showing a display example of a stereoscopic image for display. [Figure 25] FIG. 25 is an enlarged view of FIG. 24. [Figure 26] FIG. 26 is a diagram showing a display example according to a comparative example. [Figure 27] FIG. 27 is a diagram showing another display example of a stereoscopic image for display. [Figure 28] FIG. 28 is a diagram showing an example of a volume rendering image in which the transparency of the first region is set to an intermediate value.

MODE FOR CARRYING OUT THE INVENTION

[0011] [Embodiment] Hereinafter, an image processing apparatus and an image processing program according to an embodiment will be described.

[0012] <Regarding the overall configuration of the X-ray imaging apparatus> The overall configuration of an X-ray imaging apparatus including an image processing apparatus will be described. FIG. 1 is a schematic front view showing the X-ray imaging apparatus 20.

[0013] For convenience of explanation, directions will be defined. The XYZ Cartesian coordinate system is a Cartesian coordinate system defined in a three-dimensional space in which the X-ray imaging device 20 is installed. The Z-axis direction is the body axis direction of the imaging subject M when held by the X-ray imaging device 30 (described later). In the case of a standing-type X-ray imaging device 10 as in this embodiment, the Z-axis direction is the up-down direction along the direction of gravity. The Y-axis direction is the direction perpendicular to the Z-axis direction, and the X-axis direction is the direction perpendicular to both the Z-axis and Y-axis directions. In this embodiment, the Y-axis direction is the front-to-back direction of the head P of the imaging subject M held by the subject support unit 46 (described later), and the X-axis direction is the left-to-right direction of the head. A two-dimensional direction or plane consisting of multiple directions, such as the X-axis direction, the Y-axis direction, and their combined direction, may be represented as "XY." For example, an "XY plane" is a plane perpendicular to the Z-axis direction.

[0014] The X-ray imaging device 20 includes an X-ray imaging execution device 30 and an image processing device 50.

[0015] The X-ray imaging execution device 30 is configured to be able to perform X-ray CT (Computed Tomography) imaging. The X-ray imaging execution device 30 performs X-ray CT imaging and collects X-ray imaging data (also called projection data). The collected X-ray imaging data is output to the image processing device 50. The image processing device 50 generates X-ray CT image data based on the X-ray imaging data. The X-ray CT image data is three-dimensional volume data. Furthermore, the image processing device 50 generates a stereoscopic image for display suitable for observation or diagnosis based on the X-ray CT image data.

[0016] The X-ray imaging execution device 30 may be configured to be able to perform at least one of simple transmission X-ray imaging, panoramic X-ray, and cephalometric imaging in addition to X-ray CT imaging. In this case, the image processing device 50 may be configured to be able to generate at least one of simple transmission image data, panoramic X-ray image data, and cephalometric imaging image data based on the X-ray imaging data.

[0017] In this application, when the phrase "at least one" is used in relation to multiple items connected by a conjunction such as "and," the "at least one" does not refer to each individual item, but to all of the multiple items connected by "and." Therefore, for example, when the phrase "at least one of A and B" is used, it means "in the case of A," "in the case of B," or "in the case of both A and B."

[0018] More specifically, the X-ray imaging execution device 30 includes an X-ray generator 34, an X-ray detector 36, a swivel support unit 32, a drive mechanism 40, and an object support unit 46. The X-ray generator 34 and the X-ray detector 36 are supported by the swivel support unit 32. The swivel support unit 32, the drive mechanism 40, and the object support unit 46 are supported by a support frame 38 at positions above the floor.

[0019] More specifically, the support frame 38 includes a base 38a, support columns 38b, and an upper frame 38c. The base 38a extends horizontally on the floor. The support columns 38b are supported by the base 38a in a vertical position extending upward from the floor. The base end of the upper frame 38c is supported in a cantilevered manner by the support columns 38b. The upper frame 38c extends outward from the support columns 38b in the horizontal direction. The upper frame 38c may be movable up and down relative to the support columns 38b by an electric motor or manually.

[0020] The swivel support part 32 includes a body part 32a formed in an elongated shape, a generator support part 32b, and a detector support part 32c. A collimator 32s that collimates the generated X-rays is provided in front of the X-ray irradiation port of the X-ray generator 34 in the generator support part 32b. For example, the collimated X-rays are used to form an X-ray cone beam for X-ray CT imaging or an X-ray slit beam for panoramic X-ray imaging.

[0021] A swivel support shaft 32aS protrudes upward from the longitudinal middle of the body 32a. The upper end of the swivel support shaft 32aS is rotatably supported by a bearing of a drive mechanism 40 provided in the upper frame 38c. The swivel support part 32 can rotate around the central axis X of the swivel support shaft 32aS while being suspended by the upper frame 38c via the drive mechanism 40.

[0022] The revolving support shaft 32aS may be moved along the XY plane, for example, may be rotated, in synchronization with the rotation of the revolving support unit 32. The movement of the revolving support shaft 32aS may be performed by an electric motor for applying an XY movement force that is separate from the electric motor for applying a rotation force to the revolving support unit 32. When the revolving support shaft 32aS is rotated in synchronization with the rotation of the revolving support unit 32 about the revolving support shaft 32aS, the rotation diameter of the generator support unit 32b or the detector support unit 32c can be made larger or smaller than the rotation diameter determined by the distance of the generator support unit 32b or the detector support unit 32c from the revolving support shaft 32aS.

[0023] In the following description, the center of curvature of the rotational locus along which the generator support part 32b or the detector support part 32c actually moves is the rotational center X, regardless of whether the rotational support shaft 32aS rotates or not.

[0024] The generator support 32b is formed in a case shape capable of housing the X-ray generator 34. The detector support 32c is supported in a case shape capable of housing the X-ray detector 36. The generator support 32b and the detector support 32c are supported by the trunk 32a. The rotation center X is set to pass between the generator support 32b and the detector support 32c. A gap is set between the generator support 32b and the detector support 32c in which a head P can be placed. For example, the generator support 32b is supported in a hanging manner at one end of the trunk 32a, and the detector support 32c is supported in a hanging manner at the other end of the trunk 32a. Then, with the head P placed between the generator support 32b and the detector support 32c, the generator support 32b and the detector support 32c can rotate around the head P.

[0025] The X-ray generator 34 is an X-ray source that generates X-rays and includes, for example, an X-ray tube. The X-ray generator 34 is housed in the generator support part 32b with the X-ray irradiation direction facing the detector support part 32c.

[0026] The X-ray detector 36 is a sensor that detects X-rays and includes, for example, a flat panel detector (FPD) or an X-ray image intensifier (II). The X-ray detector 36 is housed in the detector support part 32c with its detection surface facing the detector support part 32c.

[0027] When the head P is positioned between the generator support part 32b and the detector support part 32c, the head P is positioned between the X-ray generator 34 and the X-ray detector 36. In this state, the X-ray generator 34 irradiates X-rays toward the head P. The X-ray detector 36 receives and detects the X-rays that have passed through the head P.

[0028] The drive mechanism 40 drives the swivel support part 32 to rotate. For example, the drive mechanism 40 includes an electric motor 41 incorporated in the upper frame 38c. The rotational drive force of the electric motor 41 is transmitted to the swivel support shaft 32aS of the swivel support part 32. The rotational drive force of the electric motor 41 may be transmitted directly to the swivel support shaft 32aS, or may be transmitted to the swivel support shaft 32aS via a transmission mechanism such as a motor or a pulley.

[0029] The drive mechanism 40 may be provided with an electric motor 41XY for driving and moving a bearing portion that supports the revolving support shaft 32aS. The bearing portion is guided in the XY directions by a bearing portion movement guide and moves along the XY plane by the driving force of the electric motor 41XY. For example, the revolving support shaft 32aS can be revolved by revolving the bearing portion.

[0030] As described above, the swivel support part 32 can rotate with the head P positioned between the generator support part 32b and the detector support part 32c. During rotation, the X-ray generator 34 irradiates X-rays toward the head P, and the X-ray detector 36 receives and detects the X-rays that have passed through the head P. This allows the X-ray detector 36 to detect X-rays that have passed through the head P from multiple directions.

[0031] The subject support part 46 is a holder that holds the subject to be photographed, i.e., the head P of the person M. Fig. 2 is an explanatory diagram showing the state in which the subject support part 46 supports the head P. Fig. 3 is an explanatory diagram showing the positional relationship between the subject support part 46 and the dental arch region Ar.

[0032] As shown in FIGS. 1 to 3, the subject support section 46 includes, for example, a chin rest 46a, a head holder 46b, and a subject support frame 46c.

[0033] The subject support frame 46c is formed in an elongated shape. The base end of the subject support frame 46c is supported in a cantilevered manner by the support column 38b. The subject support frame 46c extends horizontally from the support column 38b. The subject support frame 46c extends from a position lower than the generator support part 32b and the detector support part 32c toward the inner periphery of the rotation path of the generator support part 32b and the detector support part 32c.

[0034] The chin rest 46a and head holder 46b are supported at the tip of the subject support frame 46c. The chin rest 46a and head holder 46b are supported so as to face between the X-ray generator 34 and the X-ray detector 36 supported by the swivel support part 32. The head P supported by the subject support part 46 is held at a fixed position between the X-ray generator 34 and the X-ray detector 36 while the X-ray generator 34 and the X-ray detector 36 are rotating.

[0035] The chin rest 46a supports the tip of the lower jaw of the head P, thereby fixing the maxillofacial region A in a fixed position. The maxillofacial region refers to the jaw including the upper and lower teeth, and the maxillofacial region A refers to the region including the maxillofacial region. The maxillofacial region A includes the dental arch region Ar and the alveolar bone region Alv (see FIG. 7 ). The dental arch refers to the curved line in which multiple teeth are arranged in an arch shape from the anterior teeth to the molars, and the dental arch region Ar refers to the region including multiple teeth arranged along such a dental arch. Furthermore, the dental alveolus refers to the depression into which the roots of the teeth fit, and the alveolar bone is the bone that forms multiple alveoli into which multiple teeth arranged along the dental arch fit, and the alveolar bone region Alv refers to the region including such alveolar bone. The alveolar bone region Alv may be considered to be only the region including the alveoli, or may be considered to be the region from the region including the alveoli to the temporomandibular joint region. The alveolar bone region Alv may also be considered to be the region including the alveoli and a portion of the region connected to the temporomandibular joint region. A part of the region where the alveolus is located may be considered to be the alveolar bone region Alv. The alveolar bone region in the tissue region to be displayed, which will be described later, may be considered to be the alveolar bone region Alv.

[0036] In the present application, the maxillofacial region to be subjected to X-ray CT imaging and the maxillofacial region to be displayed do not necessarily have to be the entire region. For example, it is possible to image only one of the upper and lower jaws, only one of the left and right regions, only the right region of the upper or lower jaw, only the left region of the upper or lower jaw, only the region near the front teeth, or only the upper or lower jaw portion near the front teeth.

[0037] It is also possible to obtain image data from X-ray CT scans of a wide area, but only process a portion of it. For example, it is possible to obtain image data from X-ray CT scans of the entire maxillofacial region, but extract only the local area of ​​interest for image processing.

[0038] The subject support portion 46 may include a bite piece to be bitten by the upper and lower front teeth in addition to or instead of the chin rest 46a.

[0039] The head holder 46b holds the head P from both sides, thereby positioning the head P in the X-axis direction. In the subject support section 46, the chin rest 46a or the head holder 46b may be omitted.

[0040] The subject support section 46 may be movable up and down relative to the support column 38b by an electric motor or manually.

[0041] The positions of the swivel support unit 32 and the subject support unit 46 are adjusted with reference to the support column 38b. Therefore, the positions and swivel trajectories of the X-ray generator 34 and the X-ray detector 36 relative to the head P supported by the subject support unit 46 can be known information. Furthermore, in the volume data generated based on the X-ray imaging data, the positions of the dental arch region Ar and the alveolar bone region Alv can also be known information.

[0042] With the head P supported by the subject support part 46, the swivel support part 32 can be rotated to rotate the X-ray generator 34 and the X-ray detector 36 around the head P. As a result, the X-ray imaging execution device 30 performs X-ray CT imaging of the head P.

[0043] The image processing device 50 is a computer that processes image data of the maxillofacial region obtained by X-ray CT imaging using the X-ray imaging execution device 30. Projection data obtained by X-ray CT imaging of the maxillofacial region is an example of image data of the maxillofacial region obtained by X-ray CT imaging. In this embodiment, the image processing device 50 is communicably connected to the X-ray imaging execution device 30 and controls the operation of the X-ray imaging execution device 30. In addition, in this embodiment, the image processing device 50 generates volume data as image data including the maxillofacial region based on detection data from the X-ray detector 36 obtained by X-ray CT imaging.

[0044] At least one of the process for controlling the operation of the X-ray imaging execution device 30 and the process for generating volume data may be executed by a computer separate from the image processing device 50.

[0045] <Electrical configuration> FIG. 4 is a block diagram showing an example of the electrical configuration of the image processing device 50.

[0046] The image processing device 50 includes at least one processor 52 and a storage device 54 as a storage unit.

[0047] The storage device 54 is a non-transitory storage medium, such as a flash memory or a hard disk drive, and stores volume data 54a of the maxillofacial region A as image data including the alveolar bone region Alv.

[0048] The storage device 54 stores a program 54b describing a processing procedure for generating a stereoscopic image for display based on the volume data 54a. The stereoscopic image for display is an image generated by rendering the volume data 54a so as to be suitable for display on the display device 58. For example, the stereoscopic image for display may be an image that two-dimensionally expresses how the volume data 54a appears from an arbitrary viewpoint. In other words, the stereoscopic image for display may be a stereoscopic image displayed in two dimensions. The viewpoint may be set in advance at a predetermined position in the coordinate system of the volume data, or may be set at an arbitrary position by the user.

[0049] The characteristics of a stereoscopic image are as follows: Consider the image of an object when viewed stereoscopically.

[0050] Figure 5(a) illustrates a simple cube CB1. Cube CB1 has eight vertices: Pa, Pb, Pc, Pd, Pe, Pf, Pg, and Ph. The vertices closest to the observation viewpoint are considered near, and the vertices farther from the observation viewpoint are considered far. Vertex Pg is related to face SF1, consisting of at least vertices Pa, Pb, Pc, and Pd, located closer to the line of sight. In other words, vertex Pg is located farther from face SF1 than face SF1. If cube CB1 has a transparency of 0%, vertex Pg is invisible, as in the stereoscopic image IA of Figure 5(b). If cube CB1 has a transparency greater than 0%, vertex Pg is obscured by the vertex closer to the line of sight, as in the stereoscopic image IB of Figure 5(c), resulting in a lack of clarity. Thus, a stereoscopic image can be considered a three-dimensional image in which the objects farther from the line of sight along the line of sight from the observation viewpoint are less clearly visible than the objects closer to the line of sight.

[0051] The stereoscopic image may be an image with a strong sense of three-dimensionality that utilizes human left-right parallax so that it can be observed with a VR headset worn on the head.

[0052] The program 54b may include an imaging program that receives various instructions related to X-ray imaging and controls the drive mechanism 40, the X-ray generator 34, the X-ray detector 36, etc. in accordance with the instructions to control the X-ray CT imaging operation.

[0053] The program 54b may include a program for generating the volume data 54a based on the detection data from the X-ray detector 36 after X-ray CT imaging.

[0054] The processor 52 is an electric circuit and is configured by a CPU (Central Processing Unit), etc. The processor 52 executes the program 54b, thereby realizing various processing functions of the processor 52.

[0055] The processor 52 has an image processing function, for example, as a display 3D image generator 52a, as a functional block realized by executing the program 54b. In other words, the processor 52 is an example of an image processing unit C52. In the case where there is a main circuit consisting of a CPU and a sub-circuit subordinate to the main circuit, the main circuit and the sub-circuit may be considered to be collectively included in the processor 52. The display 3D image generator 52a is a processing block that generates a display 3D image based on the volume data 54a as image data. The image processing function will be described in more detail with reference to the flowchart of FIG. 6.

[0056] In this embodiment, the processor 52 may have processing functions as an operation control unit 52b and a volume data generation unit 52c. The operation control unit 52b is a processing block that controls the X-ray CT imaging operation of the X-ray imaging execution device 30, and the volume data generation unit 52c is a processing block that generates volume data 54a from the X-ray CT imaging data.

[0057] Note that some or all of the functions implemented in the processor 52 may be implemented in hardware using a dedicated logic circuit, etc. Also, some or all of the functions implemented in the processor 52 may be processed in an integrated manner by one processor, or may be processed in a distributed manner by multiple processors.

[0058] The image processing device 50 may be connected to the X-ray imaging execution device 30 , an operation reception unit 56 , and an external information source 57 via an interface circuit 55 .

[0059] The operation reception unit 56 is a man-machine interface that receives support operations from a user, and may be configured with at least one of a switch, a keyboard, a touch panel, and a mouse. In Fig. 1, a mouse 56a and a keyboard 56b are illustrated as examples of the operation reception unit 56.

[0060] The external information source 57 is an information source that is not located within the image processing device 50 but is located outside the image processing device 50. The external information source 57 may be, for example, an external server that is located outside the image processing device 50 and connected via a communication line. The volume data 54a may be stored in the external information source 57. Information about the subject M associated with the volume data 54a may be stored in the external information source 57. The information about the subject M may be, for example, a name, a gender, or an identification code.

[0061] The image processing device 50 may be connected to a display device 58. The display device 58 is a display device that displays a stereoscopic image for display, and is, for example, a liquid crystal display device or an organic EL (Electroluminescent) display device. The image processing device 50 and the display device 58 may be integrated.

[0062] <Example of processing in image processing device> 6 is a flowchart showing an example of volume data generation processing and an example of a stereoscopic image for display generation processing performed by the image processing device 50. Specific processing is performed by the image processing unit C52.

[0063] That is, the X-ray imaging execution device 30 performs X-ray CT imaging by rotating the X-ray generator 34 around the head P. As a result, projection data corresponding to the distribution of X-ray absorption coefficients of the head P is obtained for each of the X-rays projected from multiple directions onto the head P.

[0064] In step S1, the image processing device 50 calculates a three-dimensional distribution of X-ray absorbance of the head P based on projection data from multiple directions, and generates volume data 54a. The volume data 54a is data that includes, for example, multiple voxels arranged three-dimensionally according to the position of the head P, and each of the multiple voxels has a voxel value that indicates X-ray absorbance. The voxel value may be understood to be a CT value based on the X-ray absorption coefficient.

[0065] In this embodiment, the X-ray imaging execution device 30 performs X-ray CT imaging to include the maxillofacial region A of the head P. Therefore, the volume data 54a includes the dental arch region Ar and the alveolar bone region Alv.

[0066] The generated volume data 54 a is stored in the storage device 54 .

[0067] In the next step S2, it is determined whether or not a display instruction has been issued. For example, it is determined that a display instruction has been issued when a display instruction is input by the user via the operation receiving unit 56. The process of step S2 is repeated until it is determined that a display instruction has been issued, and if it is determined that a display instruction has been issued, the process proceeds to step S3.

[0068] In step S3, initial continuous cross sections are set. The initial continuous cross sections are cross sections that are initially set as continuous cross sections that curve along the alveolar bone region Alv. An example of continuous cross sections that curve along the alveolar bone region Alv will be described later.

[0069] After the initial serial cross sections are set in step S3, the process proceeds to step S4. In step S4, the initial serial cross sections are set as display serial cross sections to be used for generating a stereoscopic image for display based on the volume data 54a. As a result, in the alveolar bone region Alv, display serial cross sections that curve along the alveolar bone region Alv are set.

[0070] Steps S3 and S4 execute a process of setting continuous cross sections that curve along the alveolar bone region Alv in the alveolar bone region Alv.

[0071] In the next step S5, a process for changing the transparency of the volume data 54a is executed based on the sequential cross sections for display. More specifically, the transparency of a first region located within the alveolar bone region Alv of the volume data 54a, which is located within one side of the sequential cross sections for display as a boundary, is made greater than the transparency of a second region located within the other side of the sequential cross sections for display as a boundary. The process for making the transparency greater is referred to as a transparency promotion process, and the process for making the transparency of the first region greater than the transparency of the second region is referred to as a first region transparency promotion process.

[0072] Transparency is a measure of transparency. The greater the transparency, the closer it is to transparency, and the smaller the transparency, the closer it is to opaque. Transparency may be expressed as a percentage between transparent and opaque, for example. In this case, 100% transparency is transparent, and 0% transparency is opaque. Transparency between 100% and 0% is semi-transparent, and the larger the value, the closer it is to transparency.

[0073] 100% transparency may be referred to as completely transparent, and a completely transparent image may be referred to as a completely transparent image. 0% transparency may be referred to as completely opaque, and a completely opaque image may be referred to as a completely opaque image. Transparency between 100% and 0% may be referred to as partially transparent, and an partially transparent image may be referred to as an partially transparent image.

[0074] In the next step S6, a volume-rendered stereoscopic image for display is generated based on the volume data 54a for which the transparency has been set, and the stereoscopic image for display is displayed on the display device 58. The image for display may be an image that has been surface-rendered based on the volume data 54a.

[0075] Steps S5 and S6 execute a process of generating a stereoscopic image for display in which the transparency of the first region bounded by the continuous cross sections for display is displayed greater than the transparency of the second region. Steps S5 and S6 generate a stereoscopic image for display in which the transparency of the first region is greater than the transparency of the second region as a display result. Therefore, it is not essential to generate intermediate data in which transparency is set in association with each voxel of the volume data 54a.

[0076] For example, in step S5, transparency may be set for at least one of the voxels in the first region and the second region of the volume data 54a. In this case, in step S6, a rendering process may be performed based on the volume data 54a with the transparency set, to generate a stereoscopic image for display. For example, in step S5, the transparency of the first region is set to 100 percent, and the transparency of the second region is set to 0 percent. In this case, when a stereoscopic image for display seen from the first region is generated in step S6, a stereoscopic image for display is generated in which the first region is made invisible and the second region is made visible. Also, for example, in step S5, the transparency of the first region is set to 50 percent, and the transparency of the second region is set to 0 percent. In this case, when a stereoscopic image for display seen from the first region is generated in step S6, a stereoscopic image for display is generated in which the second region can be observed through the semi-transparent first region.

[0077] Also, for example, if each voxel value of the volume data 54a indicates a display density, setting the transparency to 100% may be considered to be setting the voxel value to 0. Therefore, for example, in step S5, the voxel value of the first region may be set to 0. In this case, when a stereoscopic image for display viewed from the first region is generated in step S6, the stereoscopic image for display is generated in which the first region is made invisible and the second region is made visible. Setting the voxel value of the first region to 0 may be considered to be deleting the image of the first region and generating and displaying the stereoscopic image for display.

[0078] In the next step S7, it is determined whether or not an operation to change the position of the display serial cross sections has been accepted. The operation to change the position of the display serial cross sections is performed by the user operating the operation accepting unit 56. For example, an operation to change the scale or the position of the display serial cross sections forward, backward, left, or right may be accepted by operating the mouse 56a. More specifically, an operation to change the scale of the display serial cross sections or the position of the display serial cross sections forward, backward, left, or right may be accepted by operating the wheel of the mouse 56a. In addition, an operation to change the position of the display serial cross sections may be accepted by operating the keyboard or by touching the touch screen. If it is determined in step S7 that a change operation has been accepted, the process proceeds to step S10.

[0079] In step S10, the changed consecutive cross sections are set as consecutive cross sections for display. Thereafter, the process proceeds to step S5, and the above processing is repeated.

[0080] If it is determined in step S7 that no operation for changing the position of the continuous cross sections for display has been performed, the process proceeds to step S8.

[0081] In step S8, the display of the stereoscopic image for display in step S6 continues.

[0082] In the next step S9, it is determined whether or not an instruction to end the display has been given. The instruction to end the display is given by the user operating the operation reception unit 56. For example, the instruction to end the display is input by operating the pointer of the mouse 56a, operating the keyboard, etc. If it is determined that an instruction to end the display has not been given, the process returns to step S7 and the subsequent processes are repeated. If it is determined that an instruction to end the display has been given, the process for display is terminated.

[0083] <Continuous cross-sections curved along the alveolar bone region> Fig. 7 is an explanatory diagram showing an example of setting successive cross sections for the alveolar bone region. Fig. 7 is a cross section along the XY plane, showing the alveolar bone region Alv and dental arch region Ar of the mandible.

[0084] The continuous cross sections Q1 and Q2 curved along the alveolar bone region Alv are continuous cross sections that curve in a U-shape along the direction in which the multiple alveoli 102 are arranged in the alveolar bone 100. Because the roots of the teeth (tooth regions) 110 are embedded in each of the multiple alveoli 102, the continuous cross section Q1 curved along the alveolar bone region Alv may be understood to have the same shape as the continuous cross section that curves in a U-shape along the direction in which the teeth 110 are arranged in the tooth row supported by the alveolar bone 100.

[0085] For example, continuous cross sections Q1 may be set that curve along the alveolar bone region Alv, with the tooth root 112 as a reference. In this case, the continuous cross sections Q1 may be set as cross sections that have the same width in the height direction but are continuous. Note that the tooth root 112 of the tooth 110 may be considered to coincide with the deepest part of the alveolus 102. Therefore, the continuous cross sections Q1 that curve along the multiple tooth roots 112 may be considered to be continuous cross sections Q1 that curve along the deepest parts of the multiple alveolus 102.

[0086] A single tooth may have multiple roots. In this case, the position of the center of the root tip of each root may be regarded as the position of the root 112. The center may be the center of gravity of the figure formed by the multiple root tips as viewed from the Z direction.

[0087] In this case, the continuous cross section curved along the alveolar bone region Alv may be a cross section having the same shape continuous in the height direction.

[0088] Furthermore, for example, continuous cross sections Q2 may be set that curve along the alveolar bone region Alv, based on the outer surface 100a or the inner surface 100b of the alveolar bone 100. In FIG. 7, the continuous cross sections Q2 are set along the outer surface 100a. The continuous cross sections may be set inside the outer surface 100a, or between the outer surface 100a and the inner surface 100b. In this case, within the height range in which the alveolar bone 100 exists, the continuous cross sections Q2 may be determined for each coordinate in the height direction (Z-axis direction). Therefore, in this case, the continuous cross sections Q2 may be set as cross sections whose shape changes continuously in the height direction.

[0089] The continuous cross sections Q1 and Q2 are along the alveolar bone region Alv. Therefore, the continuous cross sections Q1 and Q2 are likely to be set so as to continuously cross the plurality of teeth 110. Preferably, the continuous cross sections Q1 in particular are likely to be set so as to continuously cross the vicinity of the roots of the plurality of teeth 110. By observing the alveolar bone 100 and teeth 110 that appear in the continuous cross sections Q1 and Q2, it is easy to observe the plurality of teeth 110 simultaneously and as a whole.

[0090] 7, if the cross section Qp is a plane, the number of teeth 110 that can be crossed by the cross section Qp will be smaller than the number of teeth 110 that can be crossed by the consecutive cross sections Q1 and Q2. Furthermore, the positions at which the cross section Qp can cross each tooth 110 will vary greatly in the buccolingual direction. For this reason, even if the alveolar bone 100 and teeth 110 that appear on the cross section Qp are observed, it is difficult to observe multiple teeth 110 simultaneously and as a whole.

[0091] As shown in FIG. 8, the continuous cross sections may be configured to be composed of a plane extending in the up-down direction of the subject's head and in a direction curving along the horseshoe shape of the dental arch. FIG. 8 shows a perspective view of the continuous cross section Q1. The continuous cross section Q1 is configured to be composed of a plane extending in the up-down direction UD of the head and in a direction HS that intersects with the direction UD and curving along the horseshoe shape of the dental arch. The continuous cross sections are thus configured to divide the alveolar bone region into a buccal region BA and a lingual region TA. One of the buccal region BA and the lingual region TA may be designated as a first region R1, and the other as a second region R2.

[0092] In this way, the continuous cross section Q1 may be set to divide the alveolar bone region Alv into a buccal region BA and a lingual region TA, and one of the buccal region BA and the lingual region TA may be designated as the first region R1 and the other as the second region R2.

[0093] The initial consecutive cross sections may be initially set cross sections regardless of the distribution of voxel values ​​in the coordinate system of the volume data 54a. That is, X-ray CT imaging is performed with the head P supported by the subject support unit 46. Therefore, the support position of the head P in the volume data 54a has known coordinates. In the coordinate system of the volume data 54a, consecutive cross sections set assuming the dental arch region Ar or the alveolar bone region Alv included in the head P of a standard skeleton may be set as the initial consecutive cross sections.

[0094] The initial serial cross sections may be serial cross sections calculated based on image data of the maxillofacial region obtained by X-ray CT imaging. For example, they may be serial cross sections calculated based on the volume data 54a. An example of a process for calculating serial cross sections curved along the alveolar bone region Alv based on the volume data 54a will be described later.

[0095] <Transparency setting example> 9 is an explanatory diagram showing an example of setting transparency for the alveolar bone region, and is a cross-sectional view in which a part of FIG.

[0096] 9, the continuous cross sections for display are set in the alveolar bone region Alv. The continuous cross sections for display are the continuous cross sections Q1 that curve along the tooth root 112 described above.

[0097] Within the alveolar bone region Alv, a first region R1 exists within one region with the display continuous cross section Q1 as a boundary, and a second region R2 exists within the other region. The first region R1 is, for example, the buccal side of the display continuous cross section Q1. The buccal side of the display continuous cross section Q1 is the outer circumferential side of the display continuous cross section Q1. The second region R2 is the lingual side of the display continuous cross section Q1. The lingual side of the display continuous cross section Q1 is the inner circumferential side of the display continuous cross section Q1.

[0098] Conversely, the first region R1 may be the lingual side of the display continuous cross section Q1, and the second region R2 may be the buccal side of the display continuous cross section Q1. When rendering the volume data 54a, it is preferable that the transparency on the side where the viewpoint is located is high. This is because if the transparency on the viewpoint side is high, it is easy to observe the less transparent region through the more transparent region.

[0099] For example, if it is desired to observe the alveolar bone region Alv and the dental arch region Ar from the buccal side, the first region R1 may be set on the buccal side of the display continuous cross section Q1, and the second region R2 may be set on the lingual side of the display continuous cross section Q1.

[0100] Steps S5 and S6 may include processing for identifying regions of multiple teeth 110 and generating a three-dimensional image for display in which the transparency of the regions of teeth 110 is displayed less than the transparency of the first region R1.

[0101] For example, in step S5 above, a plurality of teeth 110 may be identified, and the transparency of the regions of the teeth 110 may be set to be lower than the transparency of the first region R1.

[0102] The regions of the multiple teeth 110 may be identified by, for example, performing edge extraction processing and pattern matching processing based on voxel values ​​on the volume data 54a. Image processing may be performed by machine learning, or may be performed by a general segmentation process such as a watershed algorithm, a region growing method, a graph-cut method, a level-set method, or a snake method. The regions of the multiple teeth 110 may be regions in which multiple teeth are collectively identified as a single region, or may be regions in which multiple individually recognized teeth are collectively treated as a single region.

[0103] The regions of the multiple teeth 110 may be identified, for example, by a trained model created by machine learning. The trained model is configured, for example, by a multi-layer neural network and stored in the storage device 54. The processor 52 reads out the program and parameters written in the trained model and executes an identification process, thereby identifying the regions of the teeth 110 in the volume data 54a. The trained model is generated, for example, by a machine learning device configured by a computer. The machine learning device uses multiple volume data in which the regions of the teeth 110 are distinguished as training data to generate a trained model that identifies the regions of the teeth 110 in the volume data. It is preferable that the tooth regions and the alveolar bone region are processed to become three-dimensional data independent of each other in image processing. Therefore, for example, the regions of the multiple teeth 110 may be segmented as described above, and the alveolar bone region Alv may also be segmented. By performing such processing, it is possible to, for example, display a cross-section of only one of the tooth regions and the alveolar bone region.

[0104] Then, in step S6, a three-dimensional image for display is generated and displayed by rendering the volume data 54a based on the transparency set for the region of the tooth 110, in which the transparency for the region of the tooth 110 is set lower than the transparency for the first region R1. Because the transparency for the region of the tooth 110 is lower, the tooth 110 is displayed more clearly than the first region R1 of the alveolar bone region Alv.

[0105] If the transparency of the tooth 110 is set to 0 percent and the transparency of the first region R1 is set to 100 percent, the voxel values ​​in the region of the tooth 110 are kept at their initial values, and the voxel values ​​in the first region R1 are set to 0. By rendering the volume data 54a after this setting, a stereoscopic image for display is generated and displayed in which the transparency of the region of the tooth 110 appears smaller than the transparency of the first region R1.

[0106] As an example of setting the transparency, the transparency of the first region R1 may be 100 percent, and the transparency of the second region R2 and the region of the teeth 110 may be 0 percent. In this case, the first region R1 is made invisible, and the second region R2 and the teeth 110 can be easily observed.

[0107] Examples of the display stereoscopic image Im in this case are shown in FIGS. 10 and 11. FIG. 11 is an enlarged view of FIG. 10. As shown in these figures, a cross-section of the alveolar bone region Alv cut along the continuous cross-section Q1 is displayed. In this cross-section, multiple teeth 110 are lined up along the continuous cross-section Q1. For simplicity, the illustration shows only the left side of the mandible. However, such processing may be performed when local imaging is performed during the aforementioned X-ray CT scan, or when image data from a wide area of ​​the alveolar bone region Alv is obtained and only a portion of that image data is subjected to image processing. By cutting and displaying the cross-section of the alveolar bone region Alv along the continuous cross-section Q1, the state of multiple teeth 110 embedded in the alveolar bone 100 can be easily grasped holistically and collectively. As shown in the figure, the teeth 110 may not be displayed in cross-section, allowing the observer to concentrate on observing the state of the alveolar bone 100. Furthermore, the shape of the mandibular canal and cyst along the alveolar bone region Alv (see circled area) can be easily grasped. 11 shows an enlarged image of the cyst at the center. In this way, an enlarged image may be generated with the region of interest at the center.

[0108] An image of a cross-section display may be called a cross-section display image. A target area of ​​a cross-section display may be called a cross-section display area. An image of a tooth 110 not shown in cross section may be called a non-cross-section display, and an image of a non-cross-section display may be called a non-cross-section display image. A target area of ​​a non-cross-section display may be called a non-cross-section display area.

[0109] In Figures 10 and 11, the region of the tooth 110 (dental arch region Ar) is displayed in a non-sectional view, but it may also be displayed in a sectional view, as indicated by square brackets in Figure 10. In this case, the sectional view may be cut along the continuous sectional view Q1. In this case, similar to the alveolar bone region, it may be considered that one side of the continuous sectional view Q1 is the boundary, and the other side is the first region TR1 of the tooth region, and the other side is the second region TR2 of the tooth region. The tooth region may be switched between a sectional view and a non-sectional view; for example, in Figures 10 and 11, the tooth region may be switched between a sectional view and a non-sectional view. The switching display may be performed by accepting an operation, or may be automatically switched by displaying for a predetermined period of time.

[0110] The continuous cross section Q1 may be set to divide the region of the tooth 110 (dental arch region Ar) into a buccal region TBA of the tooth region and a lingual region TTA of the tooth region. The transparency of the first region TR1 of the tooth region and the transparency of the second region TR2 of the tooth region are set in the same manner as the transparency of the first region R1 and the second region R2.

[0111] Regarding one of the buccal region and the lingual region being the first region and the other being the second region, this may be unified between the alveolar bone region Alv and the region of the tooth 110. That is, when the buccal region BA of the alveolar bone region Alv is the first region R1 and the lingual region TA is the second region R2, the region of the tooth 110 is also defined as the buccal region TBA as the first region TR1 of the tooth region and the lingual region TTA as the second region TR2 of the tooth region. When the buccal region BA of the alveolar bone region Alv is the second region R2 and the lingual region TA is the first region R1, the region of the tooth 110 is also defined as the buccal region TBA as the second region TR2 of the tooth region and the lingual region TTA as the first region TR1 of the tooth region.

[0112] A common continuous cross section Q1 may be set for the tooth 110 region and the alveolar bone region Alv, or individual continuous cross sections may be set as described below. The image processing unit C52 may also set a dental arch continuous cross section TQ1 that curves along the tooth 110 region (dental arch region Ar) for the tooth 110 region. The dental arch continuous cross section TQ1 may be set to separate the dental arch buccal region TBA and the dental arch lingual region TTA for the tooth 110 region. The dental arch continuous cross section TQ1 may be continuous with the continuous cross section Q1, or may be discontinuous. The dental arch continuous cross section TQ1 may overlap the continuous cross section Q1 at the same position in the buccolingual direction, or may be set at a different position in the buccolingual direction.

[0113] The transparency of the first tooth region TR1 and the second tooth region TR2 are set in the same manner as the first region R1 and the second region R2. One of the buccal region and the lingual region is set as the first region and the other as the second region, and this may be the same for the alveolar bone region Alv and the tooth 110 region, just as in the case of dividing the tooth 110 region by the continuous cross section Q1.

[0114] The movements of the continuous section Q1 and the continuous dental arch section TQ1 may or may not be independent of each other. Therefore, the following operations are possible. For example, one of the continuous section Q1 and the continuous dental arch section TQ1 may remain stationary and only the other may be moved, or the continuous section Q1 and the continuous dental arch section TQ1 may be moved in opposite directions. They may also move synchronously in the same direction. When they move in the same direction, they may move while overlapping at the same position in the buccolingual direction.

[0115] The region of the tooth 110 may be switchable between a cross-sectional view and a non-cross-sectional view.

[0116] Displaying a completely opaque cross section may be called a completely opaque cross section display, and an image of a completely opaque cross section display may be called a completely opaque cross section display image. Displaying an incompletely transparent cross section may be called an incompletely transparent cross section display, and an image of an incompletely transparent cross section display may be called an incompletely transparent cross section display image.

[0117] The cross-section of the second region may be displayed completely opaque or partially transparent. The cross-section of the second region can be displayed, for example, by making the entire second region completely opaque or partially transparent. The target tissue region for image processing, displayed on the display device to indicate the cross-section display region, may be referred to as the display target tissue region. For example, the region shown in the display stereoscopic image Im in FIG. 10, which includes both the tooth region consisting of the teeth 110 and the alveolar bone region Alv consisting of the alveolar bone 100, is an example of the display target tissue region. Since the second region is a region cut along the continuous cross-section Q1 and has a lower transparency than the first region, the second region can be displayed as a cross-section by making the second region completely opaque or partially transparent, as long as the surface of the continuous cross-section Q1 is visible.

[0118] The first region may be displayed completely or partially transparent. For example, the cross-section of the second region can be displayed by making the entire first region completely or partially transparent and making it more transparent than the second region.

[0119] Providing a completely opaque non-cross-sectional display may be called a completely opaque non-cross-sectional display, and an image of a completely opaque non-cross-sectional display may be called a completely opaque non-cross-sectional display image. Providing an incompletely transparent non-cross-sectional display may be called an incompletely transparent non-cross-sectional display, and an image of an incompletely transparent non-cross-sectional display may be called an incompletely transparent non-cross-sectional display image.

[0120] The non-sectional display of the tooth region may be performed in a completely opaque manner or in a partially transparent manner. For example, the non-sectional display of the tooth region can be achieved by making the entire tooth region completely opaque or partially transparent.

[0121] However, when the tooth region is displayed in cross section, it may be displayed completely opaquely or partially transparently. In this case, the cross section of the tooth region can be displayed by, for example, making the entire second region of the tooth region completely opaque or partially transparent.

[0122] In particular, when rendering the volume data 54a, if a global illumination process is performed that calculates and renders not only direct light from the light source but also indirect light due to reflection, etc., the unevenness and front-to-back feel of the second region R2 and tooth 110 that appear in the continuous cross section Q1 can be easily grasped.

[0123] FIG. 12 is a diagram showing a display example according to a comparative example. FIG. 12 shows a display example in which the alveolar bone region Alv is cut along a plane, the cross section Qp. In this case, the number of teeth 110 appearing on the cross section Qp is fewer than the number of teeth 110 appearing when the alveolar bone region Alv is cut along a continuous cross section along the dental arch region Ar. Furthermore, the positions of the multiple teeth 110 are different in the buccolingual direction, and when the cross section Qp is aligned with the position of the root 112 of one tooth 110, it is misaligned with the roots 112 of the other teeth 110. This makes it difficult to observe the embedding of the multiple teeth 110 in the alveolar bone 100 all at once.

[0124] In contrast, when cutting along the continuous cross sections Q1 along the dental arch region Ar as in this embodiment, many teeth 110 appear on the continuous cross sections Q1, making it easy to observe the entirety and all of the teeth 110. Furthermore, since similar positions of the multiple teeth 110 appear on the continuous cross sections Q1, it is easy to observe, for example, how the multiple teeth 110 are embedded in the alveolar bone 100 all at once.

[0125] Furthermore, because the transparency of the tooth 110 region is less than the transparency of the first region R1, it is easy to observe the shape of the portion of the tooth 110 that was embedded in the first region R1. This makes it easy to observe how the tooth 110 is embedded in the second region R2 of the alveolar bone 100. In the continuous cross section Q1 along the dental arch region Ar, the many teeth 110 are displayed in a convex state, so it is easy to observe how the many teeth 110 are embedded.

[0126] <Example 1 of continuous cross section setting processing> In step S3, successive cross sections that curve along the alveolar bone region Alv may be obtained based on the volume data 54a. An example of processing for obtaining the successive cross sections will be described.

[0127] As a first setting processing example, the positions of a plurality of tooth roots 112 in the dental arch may be identified, and the continuous cross sections Q1 may be set based on the positions of the plurality of tooth roots.

[0128] 13 is a longitudinal cross-sectional view showing a state in which some teeth 110 in the volume data 54a are embedded in the alveolar bone 100. As shown in the figure, in the volume data 54a, the voxel values ​​of the outer surfaces of the teeth 110 are higher than those of the surrounding areas. For this reason, for example, in the mandibular dental arch region Ar, it is possible to determine whether each voxel value has a voxel value equivalent to the outer surface of the tooth 110 from bottom to top, and when a voxel having a voxel value equivalent to the outer surface of the tooth 110 is detected, it is determined that the position of the voxel is position P1 of the tooth root 112.

[0129] Furthermore, for example, tooth roots may be identified by three-dimensional pattern recognition or by applying a trained model that has been machine-learned using volume data in which the tooth root positions are distinguished as training data.

[0130] The continuous cross section Q1 based on the positions of the multiple tooth roots 112 may be, for example, a cross section in which a reference line determined based on the positions of the tooth roots 112 is uniformly continuous from top to bottom. Such a reference line may be a curve determined so as to minimize the sum of the squares of the distances to the tooth roots 112 on the XY plane onto which the positions of the tooth roots 112 are projected, or may be a Bezier curve or a broken line set to pass through the tooth roots 112.

[0131] The number of tooth roots 112 may be more than two, for example, three or four. In this case, the position of the center of gravity of a closed figure formed by connecting the positions of the root apices with a straight line may be set as the position of the tooth root (total tooth root position). Even when there are two tooth roots 112, the position of the center of gravity may be set as the position of the tooth root.

[0132] It is possible that the alveolar bone region Alv includes the alveolar bone regions Alv of the upper and lower jaws. In this case, the continuous cross sections Q1 may be set separately for the upper and lower jaws. Figure 7 shows an example of a lower continuous cross section Q1, which is a cross section that curves along the alveolar bone region Alv of the lower jaw, in the alveolar bone region Alv of the lower jaw.

[0133] 14 illustrates an example of an upper continuous cross section Q1, which is a cross section curved along the maxillary alveolar bone region Alv, in the maxillary alveolar bone region Alv. In the following description, to distinguish it from the mandible, it may be referred to as the maxillary alveolar bone region Alv(U) and the upper continuous cross section Q1(U). Similarly, it may be considered that the mandibular alveolar bone region and the lower continuous cross section may also be referred to as the mandibular alveolar bone region Alv(D) and the lower continuous cross section Q1(D).

[0134] As with the alveolar bone region Alv of the mandible, by identifying the position of the tooth root 112, an upper continuous cross section Q1(U) that curves along the alveolar bone region Alv(U) of the maxilla can be set.

[0135] If continuous cross sections Q1, S1(U) are set separately along the alveolar bone regions Alv, Alv(U) of the upper and lower jaws, appropriate continuous cross sections Q1, S1(U) can be set according to the shapes of the upper and lower alveolar bone regions Alv, Alv(U).

[0136] The upper and lower boundaries in the volume data 54a may be preset as known positions in the volume data 54a, or may be set at a height position a predetermined distance away from the bottom of the jawbone recognized by pattern recognition or the like, or may be set at a position between the upper and lower dental arches after processing to recognize the upper and lower dental arches, as described above.

[0137] <Example 2 of continuous cross section setting processing> When determining continuous cross sections that curve along the alveolar bone region Alv based on the volume data 54a, as a second setting processing example, the surface position of the alveolar bone region Alv may be identified, and the continuous cross sections Q2 may be set according to the distance from the surface position.

[0138] Fig. 15 is an explanatory diagram showing an example of processing for identifying the surface position of the alveolar bone region Alv. Fig. 15 is a cross-sectional view of the alveolar bone region Alv and the dental arch region Ar along the XY plane. XY axes are shown in Fig. 15.

[0139] A horizontal cross section of the alveolar bone region Alv appears in the XY plane corresponding to a predetermined height position. The anterior end of the alveolar bone region Alv is set to face downward in the XY plane. Multiple discrete x-coordinates, x(0), x(1), x(n), x(n+1), x(n+2), and so on, are set in the X-axis direction. At any x-coordinate, it is determined whether the voxel values ​​of voxels aligned in the Y-axis direction exceed (or are equal to or greater than) the value corresponding to cortical bone. This determination may be performed sequentially in the +Y direction. The x and y coordinates of voxels having voxel values ​​exceeding (or equal to or greater than) the value corresponding to cortical bone are identified as the location of the cortical bone, i.e., the surface of the alveolar bone region Alv. By performing the above process for each of the multiple x-coordinates, the surface position of the alveolar bone region Alv, here the outer surface line La, is determined. The outer surface line La may be obtained by performing edge extraction processing on the voxel values.

[0140] A continuous line L is set based on the outer surface line La. The continuous line L is a line that is set to pass through the alveolar bone region Alv based on the outer surface line La. For example, as shown in FIG. 16, a line that extends a certain distance from the continuous line L into the alveolar bone region Alv may be set as the continuous line L. The continuous line L may be set as a line that passes as close to the tooth root 112 as possible.

[0141] By repeating the above process while changing the height in the Z-axis direction, the continuous line L is obtained for each height. The set of continuous lines L in the Z-axis direction is obtained as the continuous cross section Q2 that changes in the Z-axis direction.

[0142] Similarly, for the maxilla, continuous cross sections are obtained according to the surface of the alveolar bone region of the maxilla.

[0143] In the above example, the continuous cross sections are obtained based on the buccal surface of the alveolar bone region Alv. The continuous cross sections may be obtained based on the lingual surface of the alveolar bone region Alv, or may be obtained based on both the buccal surface and the lingual surface. For example, the continuous cross sections may be located at an intermediate position between the buccal surface and the lingual surface.

[0144] <Example of changing continuous sections> A processing example of step S7 will be described in more detail. The change of the cross-sectional position may be performed, for example, by horizontally moving the continuous cross sections Q1 (moving in the horizontal direction) or by moving them in the buccolingual direction. The change of the cross-sectional position may be performed based on an operation received by the operation receiving unit 56. The operation on the operation receiving unit 56 may be, for example, a wheel operation of the mouse 56a, a combination of a key operation on the keyboard and a wheel operation of the mouse 56a, or a drag operation using the mouse 56a.

[0145] The image processor C52 changes the transparency based on the successive cross sections Q1 after the movement and generates a stereoscopic image for display. The display device 58 displays the stereoscopic image for display.

[0146] FIG. 17 shows an example in which the continuous cross-sections Q1 are translated forward. The continuous cross-sections Q1 are translated forward while maintaining their original shape. The transparency is changed based on the translated continuous cross-sections Q1, and a three-dimensional image for display is generated and displayed. The continuous cross-sections Q1 may be translated forward and backward or left and right. Translation may be considered an example of horizontal translation. Because the dental arch has a shape that extends from the anterior tooth region to the left and right molar regions, translation may generally be considered to include an element of buccal-lingual translation of the continuous cross-sections. Furthermore, translation may generally be considered to include an element of lingual-to-buccal translation across almost the entire dental arch, or an element of buccal-to-lingual translation across almost the entire dental arch. Even if a diagonal translation component is added to the translation, as long as it includes a parallel translation component, it generally includes an element of buccal-lingual translation of the continuous cross-sections. Such movements that include elements of movement in the buccolingual direction may also be considered as buccolingual movements.

[0147] Alternatively, the image processing unit C52 may automatically change the serial cross sections Q1, change the transparency based on the serial cross sections Q1 each time a change is made, generate and display a stereoscopic image for display, and allow the surgeon to stop the change at a desired position. Alternatively, the image processing unit C52 may automatically search for a lesion candidate and automatically determine the serial cross sections Q1 at the position of the lesion candidate.

[0148] 18 and 19 show examples in which the continuous cross sections Q1 are moved in the buccal-lingual direction. The movement of the continuous cross sections Q1 in the buccal-lingual direction may be understood as enlarging or reducing the continuous cross sections Q1. The movement of the continuous cross sections Q1 in the buccal direction is an enlargement of the continuous cross sections Q1, and the movement of the continuous cross sections Q1 in the lingual direction is a reduction of the continuous cross sections Q1.

[0149] The movement of the continuous cross sections Q1 may be partial. For example, the continuous cross sections Q1pt may be moved in the buccal-lingual direction only for the partial area PT1, as shown in Fig. 20. In the illustrated example, the continuous cross sections Q1pt are moved in the buccal direction.

[0150] 18 shows the enlarged continuous cross section Q1e1, in which the continuous cross section Q1 has been moved toward the cheek, i.e., enlarged. The enlarged continuous cross section Q1e1 is obtained by similarly enlarging the continuous cross section Q1 based on the lingual point Pi. The continuous cross section Q1 may also be similarly reduced to form a reduced continuous cross section.

[0151] 19 shows the enlarged continuous cross section Q1e2, which is the result of moving the continuous cross section Q1 toward the cheek by other processing. The enlarged continuous cross section Q1e2 is a line that passes through a position that is a certain distance outward from each point on the continuous cross section Q1, perpendicular to the tangential direction. The reduced continuous cross section may be set so that it passes through a position that is a certain distance inward from each point on the continuous cross section Q1, perpendicular to the tangential direction.

[0152] The consecutive cross sections may be set by combining the above-mentioned parallel movement and movement in the buccolingual direction. The movement and scaling operations may be set so that an operation applied to a part of the consecutive cross sections Q1 extends to the entire consecutive cross sections Q1 in the tissue region to be displayed.

[0153] In either case, the translated continuous cross section Q1 or the enlarged continuous cross sections Q1e1, Q1e2 are set as the continuous cross sections for display (see step S10), the transparency is changed based on the changed continuous cross sections for display, and a three-dimensional image for display is generated and displayed on the display device 58 (see steps S5 and S6).

[0154] Examples of movement of the continuous cross sections Q1 in the buccolingual direction according to geometric rules include the parallel movement of the continuous cross sections Q1 while maintaining the shape as shown in Fig. 17 and the similarity scaling of the continuous cross sections Q1 based on the lingual point Pi as shown in Fig. 18. When the image processing unit C52 receives the change operation in step 7, it moves the continuous cross sections Q1 in the buccolingual direction according to the geometric rules.

[0155] <Effects, etc.> According to the image processing device 50 configured as described above, consecutive cross sections Q1 and Q2 curved along the alveolar bone 100 are set in the alveolar bone region Alv, and a stereoscopic image for display Im is generated in which the transparency of a first region R1 located on one side of the consecutive cross sections Q1 and Q2 in the alveolar bone region Alv is greater than the transparency of a second region R2 located on the other side of the consecutive cross sections Q1 and Q2 in the alveolar bone region Alv. Therefore, the second region R2 appearing in the consecutive cross sections Q1 and Q2 curved along the alveolar bone 100 can be easily observed in the stereoscopic image for display Im. A larger number of teeth 110 are displayed side by side on the consecutive cross sections Q1 and Q2 than when the cross sections are planar. This provides a stereoscopic image for display Im suitable for observing a wider range along the alveolar bone region Alv, based on the volume data 54a of the maxillofacial region obtained by X-ray CT imaging.

[0156] Furthermore, if the successive cross sections Q1 and Q2 are determined based on the volume data 54a obtained by X-ray CT imaging, the successive cross sections Q1 and Q2 suitable for observing the alveolar bone 100 according to the skeleton of the head P that was the subject of the X-ray CT imaging can be determined.

[0157] Furthermore, by setting the continuous sections Q1, S1(U) as a lower continuous section Q1 that curves along the alveolar bone region Alv of the lower jaw and an upper continuous section Q1(U) that curves along the alveolar bone region Alv(U) of the upper jaw, a stereoscopic image for display suitable for observing a wider range along the separate upper and lower alveolar bone regions Alv, Alv(U) can be provided.

[0158] When the first region R1 is made invisible in the stereoscopic image for display Im, that is, when the first region R1 is transparent, the second region R2 is easily observed clearly in the continuous cross sections Q1.

[0159] Furthermore, if the transparency of the region of the teeth 110 is displayed less than the transparency of the first region R1 in the stereoscopic image for display Im, the teeth 110 can be easily observed.

[0160] Furthermore, if the continuous cross sections Q1 are set based on the position of the tooth root 112, it is possible to easily observe how the teeth 110 aligned along the dental arch are embedded in the alveolar bone region Alv.

[0161] Furthermore, if the continuous cross sections Q2 are set in accordance with the distance from the surface position of the alveolar bone region Alv, it is easy to observe cross sections of a uniform internal depth with reference to the surface of the alveolar bone region Alv.

[0162] Furthermore, since the continuous cross section Q2 follows the surface of the alveolar bone region Alv, the continuous cross section Q2 is a cross section that changes in the height direction. Therefore, the continuous cross section Q2 shows a cross section of the alveolar bone 100 cut obliquely with respect to the X-axis direction and the Y-axis direction. This makes it easy to observe the internal structure of the alveolar bone 100 from various directions. Furthermore, the teeth 110 are easily exposed in various directions, making them easy to observe.

[0163] Furthermore, by changing the continuous cross sections Q1 and Q2 based on an operation received by the operation receiving unit 56, the alveolar bone 100 can be observed in various cross sections.

[0164] Furthermore, by moving the continuous cross section Q1 in the buccolingual direction, the entire dental arch can be easily observed at various depths from the surface of the alveolar bone 100.

[0165] <Display color variations> As a first modification, an example in which the display color of a stereoscopic image for display is modified will be described.

[0166] That is, the display color of the second region R2 displayed on the continuous cross sections Q1 may differ depending on the position in the buccal-lingual direction.

[0167] As shown in FIG. 21 , a continuous cross section Q1 is set for the alveolar bone 100, and the set continuous cross section Q1 is set as a continuous cross section at a reference position. Boundary surfaces T1, T2, and T3 are set toward the buccal side relative to the continuous cross section Q1. The boundary surfaces T1, T2, and T3 may be surfaces obtained by reducing the continuous cross section Q1 toward the buccal side. Different display colors are set for each region of the second region R2 of the alveolar bone 100 that is divided by the continuous cross section Q1 and the boundary surfaces T1, T2, and T3. For example, the display colors may be set to change from cool to warm colors as the distance from the continuous cross section Q1 increases (e.g., toward the buccal side), or the display colors may be set to gradually change from light to dark colors as the distance from the continuous cross section Q1 increases (e.g., toward the buccal side).

[0168] The display color to be changed may be allocated according to the distance from the continuous cross-sections at the reference position in this way, but may also be allocated according to the distance from the buccal surface BSF of the alveolar bone or the distance from the lingual surface TSF of the alveolar bone. In this way, the display color to be changed may be allocated according to the buccolingual distance from a reference position surface such as the continuous cross-sections at the reference position Q1, the buccal surface BSF of the alveolar bone, or the lingual surface TSF of the alveolar bone.

[0169] The volume data 54a is subjected to rendering processing so as to present the set display color, and a stereoscopic image Imv for display is generated and displayed on the image processing device 50.

[0170] 22(a) and 22(b) show examples of display in which the display color of the second region R2 is color-coded according to its position in the buccolingual direction. The buccolingual position of the continuous cross section Q1 differs between FIGS. 22(a) and 22(b). In FIG. 22(a), the region is closer to the buccal side in the buccolingual direction, while in FIG. 22(b), the region is closer to the lingual side in the buccolingual direction. In FIG. 22(a), the display color of the alveolar bone is color CL1, while in FIG. 22(b), the display color of the alveolar bone is color CL2. In the example shown in FIG. 22, a cavity CV due to bone resorption is observed in the alveolar bone. In FIG. 22(a), the cavity CV appears small because its extent is narrow at this depth, but in FIG. 22(b), it appears large because its extent is large at this depth.

[0171] Since the alveolar bone is actually composed of a mesh-like structure inside, if the display color of the second region R2 displayed in the consecutive cross sections Q1 varies depending on the position in the buccolingual direction, the depth of the irregularities and depressions in each part of the second region R2 displayed in the consecutive cross sections Q1 can be easily grasped. In addition, the position of each part of the second region R2 in the buccolingual direction can be easily grasped (see Figure 27 below).

[0172] The display color may be displayed only at the continuous cross section Q1, but the tissues that can be seen in depth may be displayed in different colors according to the depth. For example, as shown in square brackets in Figure 22(b), different colors CL2, CL3, and CL4 may be displayed according to the depth of the cavity.

[0173] <Transparency Variation> Examples of setting the transparency are not limited to the above example. In order to be able to observe the tooth 110 through the first region R1, it is preferable that the transparency of the region of the tooth 110 is smaller than the transparency of the first region R1.

[0174] For example, the transparency of the first region R1 may be an intermediate value greater than 0 percent and less than 100 percent (e.g., 80 percent; hereinafter, transparency greater than 0 percent and less than 100 percent will be referred to simply as an intermediate value), the transparency of the second region R2 may be an intermediate value less than the transparency of the first region R1 (e.g., 50 percent), and the transparency of the region of tooth 110 may be an intermediate value less than the transparency of the second region R2 (e.g., 20 percent).

[0175] Alternatively, the transparency of the first region R1 may be an intermediate value (e.g., 80 percent), the transparency of the second region R2 may be an intermediate value (e.g., 20 percent) lower than the transparency of the first region R1, and the transparency of the region of the tooth 110 may be a value between the transparency of the first region R1 and the transparency of the second region R2 (e.g., 50 percent). If the transparency of the region of the tooth 110 is higher than the transparency of the second region R2, the tooth 110 will be displayed more transparent than the second region R2, which is suitable for observing the second region R2 while grasping the general shape of the tooth 110.

[0176] If it is desired to observe the teeth 110 closely, the transparency of the region of the teeth 110 may be less than the transparency of the second region R2.

[0177] For example, the transparency of the first region R1 may be an intermediate value (e.g., 80 percent), the transparency of the second region R2 may be an intermediate value (e.g., 50 percent) that is lower than the transparency of the first region R1, and the transparency of the region of the tooth 110 may be a value lower than that of the second region R2 (e.g., 20 percent). Because the second region R2 is displayed more transparent than the tooth 110, it is easy to observe the tooth 110 while grasping the general shape of the second region R2.

[0178] When the transparency of the first region R1 or the second region R2 is set to an intermediate value, a volume-rendered stereoscopic image for display can be generated based on the volume data 54a. Figure 23 shows a volume-rendered image in which the transparency of the first region R1 is set to an intermediate value. In this case, the internal structure of the alveolar bone region Alv can be easily grasped. Furthermore, if the difference in transparency between the first region R1 and the second region R2 is appropriately set, the second region R2 that appears in the consecutive cross sections can be easily observed.

[0179] <Other variations> In the above embodiment, an example has been shown in which a stereoscopic image for display is generated with the buccal side as the viewpoint. The viewpoint direction of the stereoscopic image for display may be variably adjusted, for example, by dragging a mouse or operating a cursor. When a stereoscopic image for display is generated and displayed with the buccal side as the viewpoint, the second region may be located on the buccal side and the first region may be located on the lingual side, with the consecutive cross sections Q1 and Q2 as the boundaries.

[0180] In this embodiment, an X-ray imaging device including an image processing device has been described. The image processing device that performs the processing for display may be a device separate from the device that performs X-ray CT imaging and the device that executes the processing for reconstructing 3D data from the captured data. For example, the image processing device may perform the image processing on image data provided from an external device via communication or a storage medium to generate a stereoscopic image for display.

[0181] In addition, in the stereoscopic image for display, the color of the tooth 110 and the color of the second region R2 may be different. For example, the tooth 110 may be displayed in an achromatic color, such as white, and the second region R2 may be displayed in a chromatic color. Furthermore, the surface of the tooth 110 may be displayed in an achromatic color, such as white, and the second region R2 may be displayed in a chromatic color.

[0182] Figures 10, 11, 12, 22, and 23 show Figures 24 to 28, which are diagrams generated by CT scanning of the actual maxillofacial region and image processing. Figure 24 corresponds to Figure 10, Figure 25 corresponds to Figure 11, Figure 26 corresponds to Figure 12, Figure 27 corresponds to Figure 22, and Figure 28 corresponds to Figure 23. However, Figures 24, 26, 27, and 28 differ from Figures 10, 12, 22, and 23 in that the processing target is the entire upper and lower jaws.

[0183] The configurations described in the above embodiment and modifications can be combined as appropriate as long as they are not mutually contradictory.

[0184] The present disclosure discloses the following aspects.

[0185] The first aspect is an image processing device that processes image data of the maxillofacial region obtained by X-ray CT imaging, and includes a memory unit that stores the image data including the alveolar bone region, and an image processing unit that generates a three-dimensional image for display based on the image data.The image processing unit performs the following processes: setting successive cross sections in the alveolar bone region that curve along the alveolar bone region; and generating, as the three-dimensional image for display, an image in which the transparency of a first region located within one side of the alveolar bone region with the successive cross sections as a boundary is displayed greater than the transparency of a second region located within the alveolar bone region with the successive cross sections as a boundary.

[0186] According to this image processing device, successive cross sections that curve along the alveolar bone region are set in the alveolar bone region, and a stereoscopic image for display is generated in which the transparency of a first region located within one side of the successive cross sections as a boundary of the alveolar bone region is greater than the transparency of a second region located within the other side of the successive cross sections as a boundary of the alveolar bone region. Therefore, the successive cross sections that curve along the alveolar bone can be easily observed in the stereoscopic image for display. This provides a stereoscopic image for display that is suitable for observing a wider range along the alveolar bone region based on image data of the maxillofacial region obtained by X-ray CT imaging.

[0187] A second aspect is the image processing device according to the first aspect, wherein the image processing unit obtains the continuous cross sections curved along the alveolar bone region based on the image data.

[0188] This allows for the determination of continuous cross sections suitable for image data obtained by X-ray CT imaging.

[0189] A third aspect is an image processing device according to the first or second aspect, wherein the alveolar bone region includes an alveolar bone region of the upper jaw and an alveolar bone region of the lower jaw, and the image processing unit may set, as the continuous cross sections, an upper continuous cross section which is a cross section that curves along the alveolar bone region of the upper jaw in the alveolar bone region of the upper jaw, and a lower continuous cross section which is a cross section that curves along the alveolar bone region of the lower jaw in the alveolar bone region of the lower jaw.

[0190] In this case, based on image data of the maxillofacial region obtained by X-ray CT imaging, a three-dimensional image for display suitable for observing a wider range along the upper and lower alveolar bone regions is provided.

[0191] A fourth aspect is an image processing device according to any one of the first to third aspects, wherein the image processing unit may generate a volume-rendered image based on the image data as the stereoscopic image for display.

[0192] This makes it easier to understand the internal structure if the transparency is set appropriately.

[0193] A fifth aspect is the image processing device according to any one of the first to fourth aspects, wherein the stereoscopic image for display may be an image in which the first region is made invisible.

[0194] In this way, when the first region is made invisible in the stereoscopic image for display, the second region is easily observed clearly in the successive cross sections.

[0195] A sixth aspect is an image processing device according to any one of the first to fifth aspects, wherein the image data includes a dental arch region in which multiple teeth are arranged in an arch shape, and the image processing unit identifies the region of the multiple teeth and generates, as the three-dimensional image for display, an image in which the transparency of the tooth region is displayed less than the transparency of the first region.

[0196] In this case, the teeth are easily observed because they are less transparent.

[0197] A seventh aspect is an image processing device according to any one of the first to sixth aspects, wherein the image data includes a dental arch region in which multiple teeth are arranged in an arch shape, and the image processing unit may identify the root position of the dental arch region and set the continuous cross-section based on the root position.

[0198] This makes it easy to observe how the teeth along the dental arch are embedded in the alveolar bone region.

[0199] An eighth aspect is an image processing device according to any one of the first to seventh aspects, wherein the image processing unit may identify the surface position of the alveolar bone region and set the continuous cross sections according to the distance from the surface position of the alveolar bone region.

[0200] This allows for easy observation of continuous cross sections according to the distance from the surface of the alveolar bone region.

[0201] A ninth aspect is an image processing device according to any one of the first to eighth aspects, further comprising an operation receiving unit that receives operations from an operator, and the image processing unit may change the continuous cross-sections based on the operations received by the operation receiving unit.

[0202] As a result, the continuous cross sections are changed by operating the operation receiving unit.

[0203] A tenth aspect is the image processing device according to the ninth aspect, wherein the image processing unit may move the continuous cross sections in a buccal-lingual direction based on an operation received by the operation receiving unit.

[0204] The successive sections moving in the buccolingual direction facilitate the observation of the entire dental arch at various depths relative to the surface of the alveolar bone region Alv.

[0205] An eleventh aspect is an image processing device according to any one of the first to tenth aspects, wherein the image processing unit may generate, as the stereoscopic image for display, an image in which the display color of the second region displayed in the successive cross sections varies depending on its position in the buccolingual direction.

[0206] This makes it easy to grasp the position in the buccal-lingual direction of each part of the second display region displayed in the continuous cross sections.

[0207] A twelfth aspect is any one of the image processing devices from the first to the eleventh aspects, in which the continuous cross sections are configured as a surface that extends in the vertical direction of the subject's head and in a direction that curves along the horseshoe shape of the dental arch, and may be configured to divide the alveolar bone region into a buccal region and a lingual region.

[0208] This makes it easier to observe the upper and lower teeth along the dental arch.

[0209] The image processing program of the 13th aspect is an image processing program for causing a computer that processes image data of the maxillofacial region obtained by X-ray CT imaging to execute the following processes: setting continuous cross sections that curve along the alveolar bone region in the alveolar bone region included in the image data; and generating a three-dimensional image for display in which the transparency of a first region located within the alveolar bone region on one side of the continuous cross sections as a boundary is displayed greater than the transparency of a second region located within the alveolar bone region on the other side of the continuous cross sections as a boundary.

[0210] According to this image processing program, successive cross sections curved along the alveolar bone are set in the alveolar bone region, and a three-dimensional image for display is generated in which the transparency of a first region located within one side of the successive cross sections as a boundary of the alveolar bone region is greater than the transparency of a second region located within the other side of the successive cross sections as a boundary of the alveolar bone region. Therefore, the successive cross sections curved along the alveolar bone can be easily observed in the three-dimensional image for display. This provides a three-dimensional image for display suitable for observing a wider range along the alveolar bone region based on image data of the maxillofacial region obtained by X-ray CT imaging.

[0211] A fourteenth aspect is an image processing device according to the sixth aspect, which enables the successive cross sections to be moved horizontally or in the buccolingual direction, and the image processing unit executes a process of changing the transparency of the successive cross sections after the movement as the three-dimensional image for display, and generating the three-dimensional image for display.

[0212] A fifteenth aspect is an image processing device according to the fourteenth aspect, which generates the stereoscopic image for display in which the tooth region is a non-sectional display image.

[0213] A sixteenth aspect is an image processing device according to the fifteenth aspect, which generates the three-dimensional image for display with the transparency of the tooth region set to 0 percent.

[0214] A seventeenth aspect is an image processing device according to the sixteenth aspect, which generates the three-dimensional image for display with the transparency of the first region set to 100%.

[0215] An eighteenth aspect is an image processing device according to the seventeenth aspect, which generates the three-dimensional image for display with the transparency of the second region set to 0 percent. [Explanation of symbols]

[0216] 11 Tooth root 20 X-ray equipment 30 X-ray imaging device 50 Image processing device 52 processors 52a Display 3D image generation unit 52b Operation control section 52c Volume data generation unit 54 Storage device 54a Volume Data 54b Program 56 Operation reception section 56a Mouse 56b keyboard 58 Display device 100 Alveolar bone 100a outer surface 100b inner surface 102 Alveolar 110 teeth 112 Tooth root A. Maxillofacial region Alv Alveolar bone region Ar dental arch region Im Display Stereoscopic Image M. Subject of photography P head Q1, Q2 continuous cross section R1 1st area R2 2nd area

Claims

1. An image processing device that processes image data of a maxillofacial region obtained by X-ray CT imaging, a storage unit that stores the image data including the alveolar bone region; an image processing unit that generates a stereoscopic image for display based on the image data; Equipped with The image processing unit A process of setting continuous cross sections that curve along the alveolar bone region in the alveolar bone region; a process of generating, as the three-dimensional image for display, an image in which a transparency of a first region located within one side of the alveolar bone region with the continuous cross-sections as a boundary is displayed greater than a transparency of a second region located within the alveolar bone region with the continuous cross-sections as a boundary on the other side; An image processing device that performs the above.

2. 2. The image processing device according to claim 1, The image processing unit An image processing device that determines the continuous cross sections that curve along the alveolar bone region based on the image data.

3. 3. The image processing device according to claim 1, the alveolar bone region includes an alveolar bone region of the upper jaw and an alveolar bone region of the lower jaw, The image processing unit sets, as the continuous cross sections, upper continuous cross sections which are cross sections that curve along the alveolar bone region of the maxilla in the alveolar bone region of the maxilla, and lower continuous cross sections which are cross sections that curve along the alveolar bone region of the mandible in the alveolar bone region of the mandible.

4. 3. The image processing device according to claim 1, The image processing device is configured to generate, as the stereoscopic image for display, a volume-rendered image based on the image data.

5. 3. The image processing device according to claim 1, The image processing device, wherein the stereoscopic image for display is an image in which the first region is made invisible.

6. 3. The image processing device according to claim 1, The image data includes a dental arch region in which a plurality of teeth are arranged in an arch shape, The image processing unit identifying regions of the plurality of teeth; an image processing device that generates, as the three-dimensional image for display, an image in which the tooth region is displayed with a transparency lower than the transparency of the first region;

7. 3. The image processing device according to claim 1, The image data includes a dental arch region in which a plurality of teeth are arranged in an arch shape, The image processing unit Identifying tooth root locations in the dental arch region; An image processing device that sets the continuous cross sections based on the tooth root position.

8. 3. The image processing device according to claim 1, The image processing unit Identifying the surface location of the alveolar bone region; An image processing device that sets the continuous cross sections according to a distance from a surface position of the alveolar bone region.

9. 3. The image processing device according to claim 1, further comprising an operation receiving unit that receives an operation by an operator, The image processing unit changes the consecutive cross sections based on an operation received by the operation receiving unit.

10. 10. The image processing device according to claim 9, The image processing unit moves the continuous cross sections in a buccal-lingual direction based on an operation received by the operation receiving unit.

11. 3. The image processing device according to claim 1, The image processing unit an image processing device that generates, as the stereoscopic image for display, an image in which the display color of the second region displayed in the continuous cross sections varies depending on the position in the buccolingual direction.

12. 3. The image processing device according to claim 1, An image processing device that configures the continuous cross sections as surfaces that extend in the vertical direction of the subject's head and in a direction that curves along the horseshoe shape of the dental arch, and that sets the alveolar bone region to be divided into a buccal region and a lingual region.

13. A computer that processes image data of the maxillofacial region obtained by X-ray CT scans. A process of setting continuous cross sections that curve along an alveolar bone region included in the image data; a process of generating a stereoscopic image for display in which a transparency of a first region located within one side of the continuous cross-sections in the alveolar bone region is displayed greater than a transparency of a second region located within the other side of the continuous cross-sections in the alveolar bone region; An image processing program for executing the above.

Images