KR102558791B1 - Method and apparatus for separating areas representing a condyle and a fossa of a joint from each other in a 3-dimensional X-ray image - Google Patents

Abstract

An apparatus for separating a condyle region of a temporomandibular joint (TMJ) from a three-dimensional X-ray image and a fossa region of the temporomandibular joint (TMJ) are disclosed. The disclosed apparatus may include a storage unit configured to store the 3D X-ray image, an input unit configured to receive a user input designating a reference point within the condyle region in the 3D X-ray image, and an image processing unit configured to define a curved plane substantially separating the condyle region and the glenoid region based on horizontal or vertical coordinates of the designated reference point.

Description

Method and apparatus for separating condyle and a fossa of a joint from each other in a 3-dimensional X-ray image}

The present invention relates to X-ray medical image processing, and more particularly, to feature extraction and segmentation processing techniques in 3-dimensional X-ray images.

In general, for dental diagnosis and treatment, images taken using Cone Beam Computational Tomography (CBCT) equipment, which compensates for the disadvantages of conventional CT, are mainly used. The representative advantage of CBCT is that the effective dose (radiation exposure) is less than that of conventional CT. In recent years, with the technological development of CBCT imaging equipment, the field of view (FOV) that can be scanned at one time has increased, and through this, it is possible to simultaneously scan the patient's teeth and oral cavity as well as the left and right Temporomandibular Joint (TMJ). Thanks to this, not only dentistry but also oral surgery can diagnose and treat TMJ disorder using the temporomandibular joint image taken by CBCT imaging equipment.

However, since the fossa at the top of the temporomandibular joint and the condyle at the bottom always move in contact, it is difficult to determine the state of the contact surface of the two parts using only the original image of the temporomandibular joint where the two parts are not separated. If you rely only on the temporomandibular joint image, there is a potential for misdiagnosis. For this reason, for accurate diagnosis and treatment of the temporomandibular joint, it is necessary to separately observe the contact surface of the condyle by separating the glenoid region and the condylar region at the top of the condyle.

In order to separate the condylar region and the glenoid region, conventionally, a manual sculpture method has been used to separate the condylar region by manually cutting out the surrounding area of the condyle region in a 3D rendering image, etc., as if sculpting. However, this method has limitations in that it is inconvenient for doctors, users, to perform, and is inefficient in terms of time, and requires a lot of trial and error to accurately cut. For this reason, this method is evaluated as not suitable for practical use in medical treatment. In addition, although several image segmentation algorithms for fully automatic segmentation of condylar and glenoid regions are known, these algorithms have disadvantages such as exponential increase in system operation time in proportion to the size of the image or guaranteeing accuracy of image segmentation only when certain conditions are satisfied.

An object of the present invention is to provide a method and apparatus for quickly and accurately separating the condylar region of a joint and the glenoid region of a joint in a three-dimensional X-ray image with simple user manipulation.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

In one aspect, an apparatus for separating a condylar region of a joint and a glenoid region of the joint in a three-dimensional X-ray image is provided. The apparatus may include a storage unit configured to store the 3D X-ray image, an input unit configured to receive a user input designating a reference point within the condyle region in the 3D X-ray image, and an image processing unit configured to define a curved plane substantially separating the condyle region and the glenoid region based on horizontal or vertical coordinates of the designated reference point.

In one embodiment, the input unit may be configured to further receive a user input designating a 3D region of interest (ROI) including the region of the joint in the 3D X-ray image.

In one embodiment, the image processing unit may be further configured to define a standard curve for each of the cross-sectional images of the 3D X-ray image. Here, one point of the standard curve may have a horizontal or vertical coordinate value that is the same as the value of the horizontal or vertical coordinate or within a range selected therefrom. The image processing unit may be further configured to generate a separation curve by adjusting the position of the one point of the standard curve and/or the width of the standard curve so that the points of the standard curve are located in the gap between the condyle region and the glenoid region for each of the cross-sectional images of the 3D X-ray image. The image processing unit may be further configured to define the curved surface using the generated separation curves.

In one embodiment, the image processing unit may be further configured to define a standard curve for each of the cross-sectional images of the 3D X-ray image. Here, one point of the standard curve may have a horizontal or vertical coordinate value that is the same as the value of the horizontal or vertical coordinate or within a range selected therefrom. The image processing unit may be further configured to construct a set of separation points by moving at least one of the points of the standard curve in a vertical or horizontal direction so that the points of the standard curve are located in a gap between the condyle region and the glenoid region, and correct the set of separation points to generate a separation curve. The image processing unit may be further configured to define the curved surface using the generated separation curves.

In an embodiment, the image processing unit may be further configured to generate a binarized cross-sectional image by binarizing the corresponding cross-sectional image, and adjust a height of the one point of the standard curve based on a change in luminance value of a pixel in the binarized cross-sectional image corresponding to the one point and/or a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points of the standard curve, which are generated as the one point of the standard curve is moved in a vertical or horizontal direction.

In one embodiment, the image processing unit generates a binarized cross-sectional image by binarizing the corresponding cross-sectional image, and a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points of the standard curve is minimized. It may be further configured to adjust the width of the curve.

In one embodiment, the image processing unit may be further configured to perform 2-dimensional smoothing filtering on a curved surface formed by the separation curves.

In one embodiment, the image processing unit may be further configured to separate the condyle region from the glenoid region and display the condyle area on a display by referring to the curved surface.

In one embodiment, the joint may include a human temporomandibular joint (TMJ).

In one aspect, a method of separating a condylar region of a joint and a glenoid region of the joint in a 3D X-ray image is provided. The method may include receiving a user input designating a reference point within the condyle region in the 3D X-ray image, and defining a curved surface substantially separating the condyle region and the glenoid region based on horizontal or vertical coordinates of the designated reference point.

In one embodiment, the method may further include receiving a user input designating a 3D region of interest including the region of the joint in the 3D X-ray image.

In one embodiment, the step of defining a curved surface that substantially separates the condyle area and the articular fossa area based on the horizontal coordinates of the designated reference point, defining a standard curve for each of the cross-sectional images of the 3D X-ray image, wherein a point of the standard curve has a horizontal or vertical coordinate value equal to or within a range selected from the horizontal or vertical coordinate value, and points of the standard curve are located in a gap between the condyle area and the articular fossa region. The method may include generating a separation curve by adjusting a height of a point and/or a width of the standard curve, and defining the curved surface using the generated separation curves.

In one embodiment, the step of defining a curved surface substantially separating the condyle region and the glenoid region based on the horizontal or vertical coordinates of the designated reference point, defining a standard curve for each of the cross-sectional images of the 3-dimensional X-ray image, wherein a point of the standard curve has a horizontal or vertical coordinate value equal to or within a range selected from the horizontal or vertical coordinate value -, points of the standard curve so that points of the standard curve are located in the gap between the condyle region and the joint region It may include constructing a set of separation points by moving at least one point of the separation points in a vertical or horizontal direction, performing the steps of generating a separation curve by correcting the set of separation points, and defining the curved surface using the generated separation curves.

In one embodiment, the step of generating a separation curve by adjusting the height and/or the width of the one point of the standard curve so that the points of the standard curve are located in the gap between the condyle area and the condyle area, generating a binarized cross-sectional image by binarizing the corresponding cross-sectional image, and moving the one point of the standard curve in a vertical or horizontal direction, resulting in a change in luminance value of a pixel in the binarized cross-sectional image corresponding to the one point and/or a point of the standard curve and adjusting a height of the one point of the standard curve based on a sum of luminance values of pixels in the binarized cross-sectional image corresponding to s.

In an embodiment, the step of generating a separation curve by adjusting the height and/or the width of the one point of the standard curve so that points of the standard curve are located in the gap between the condyle region and the glenoid region may include generating a binarized cross-sectional image by binarizing the corresponding cross-sectional image, and adjusting the width of the standard curve such that a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points on the standard curve is minimized.

In an embodiment, defining the curved surface using the generated separation curves may include performing two-dimensional flattening filtering on the curved surface formed by the separation curves.

In one embodiment, the method may further include separating the condyle region from the glenoid region by referring to the curved surface and displaying the condyle region on a display.

According to the embodiments of the present invention, the condyle region of the joint and the glenoid region of the joint are quickly and accurately separated from the 3D X-ray image with only a simple user operation, and an image thereof is presented, thereby enabling an accurate diagnosis of the temporomandibular joint. Furthermore, there is a technical effect of enabling efficient surgical planning and patient counseling.

1 is a diagram showing an embodiment of the configuration of a device for separating a condylar region of a joint and a glenoid region of a joint in a 3D X-ray image according to the present invention.
FIG. 2 is a flowchart illustrating an embodiment of a method of separating a condyle area of a joint and a glenoid area of a joint in a 3D X-ray image according to the present invention.
3 is a diagram schematically illustrating a method of designating a 3D region of interest in a 3D X-ray image according to an embodiment of the present invention.
4 is a diagram showing a photograph illustrating a cross section of a 3D region of interest selected from a 3D X-ray image according to an embodiment of the present invention.
5 is a diagram showing a photograph illustrating a cross section of another 3D region of interest selected from a 3D X-ray image according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of a user interface screen provided on a display unit by the device of FIG. 1 to allow a user to select a reference point and a 3D region of interest in a 3D X-ray image.
FIG. 7 is a diagram showing a picture of an embodiment of a binarized cross-sectional image of a 3D region of interest, and is a diagram for explaining how a standard curve is defined based on reference points designated by a user with respect to the cross-sectional image.
8 is a diagram showing a photograph of an example of a binarized cross-sectional image of a 3D region of interest in which a vertex of a standard curve is moved to a gap between the condylar region and the glenoid region.
9 is a diagram showing a picture of an embodiment of a binarized cross-sectional image of a 3D region of interest in which the width of a standard curve is adjusted.
10 is a diagram showing a photograph of an embodiment of an image in which only the condylar region is separated and displayed.

The advantages and features of the present invention and how to achieve them will become clear with reference to the detailed description of the following embodiments in conjunction with the accompanying drawings. However, the present invention will not be limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and the present embodiments merely make the disclosure of the present invention complete and those skilled in the art to which the present invention belongs. It is provided to completely inform the scope of the invention, and the present invention is only defined by the scope of the claims.

Terms used in this specification are only used to describe specific embodiments and are not intended to limit the present invention. For example, a component expressed in the singular number should be understood as a concept including a plurality of components unless the context clearly means only the singular number. In addition, in the specification of the present invention, terms such as 'comprise' or 'having' are intended only to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, and the use of these terms does not preclude the existence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Also, in the embodiments described in this specification, 'module' or 'unit' may mean a functional part that performs at least one function or operation.

In addition, unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the specification of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, in the following description, if there is a risk of unnecessarily obscuring the gist of the present invention, detailed descriptions of well-known functions or configurations will be omitted.

1 is a diagram showing an embodiment of the configuration of a device for separating a condylar region of a joint and a glenoid region of a joint in a 3D X-ray image according to the present invention.

As shown in FIG. 1 , the device 100 may include an input interface 110 , an image processing unit 120 , a storage unit 130 and a display unit 140 . The input interface 110 may include hardware and software modules for inputting user commands to perform image processing according to various embodiments of the present disclosure. The input interface 110 may be advantageously used to input various necessary commands to the image processing unit 120, input various X-ray image data such as three-dimensional X-ray image data of a patient obtained by dental tomography to the storage unit 130, or instruct some or all of the displayed images to perform various image processing accordingly. The input interface 110 may also advantageously be used to designate and input an arbitrary point on a 3D X-ray image or to designate and input a 3D region of interest (ROI) including a region of a joint. In one embodiment, the input interface 110 may include a keyboard, keypad, touchpad, mouse, etc. of a computer, but the type of input interface is not limited thereto. For example, the input interface 110 may include a graphical user interface controllable using the aforementioned input devices. The display unit 140 is for displaying images formed according to various embodiments of the present invention, and may include various display devices such as an LCD display, an LED display, an AMOLED display, and a CRT display.

The storage unit 130 may be used to store various X-ray images, such as a three-dimensional X-ray image of a patient obtained by dental tomography. The storage unit 130 may be used to store image data of intermediate results resulting from image processing according to various embodiments of the present invention, resultant image data obtained by performing image processing according to various embodiments of the present invention, and variable values necessary for performing image processing according to various embodiments of the present invention. In various embodiments, the storage unit 130 may store the various images described above in a Digital Imaging and Communications in Medicine (DICOM) format or a general image file format (BMP, JPEG, TIFF, etc.). The storage unit 130 may further store software/firmware necessary for implementing the image processing unit 120 . The storage unit 130 may include a flash memory type, a hard disk type, a MultiMedia Card (MMC), a card-type memory (eg, a Secure Digital (SD) card or an eXtream Digital (XD) card), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read-Only Memory (ROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), and a PROM ( Programmable Read-Only Memory), a magnetic memory, a magnetic disk, and an optical disk, but those skilled in the art will recognize that the implementation form of the storage unit 130 is not limited thereto.

The image processing unit 120 reads all or part of the 3D X-ray image data from the storage unit 130 and implements an image processing function that separates the condylar region of the joint and the glenoid region of the joint in the 3D X-ray image according to various embodiments of the present invention. The image processing unit 120 may be configured to prompt the user to designate a 3D region of interest and an arbitrary point within the 3D region of interest in the 3D X-ray image including the region of the joint, and store information on the above-described 3D region of interest and the arbitrary point designated by the user and input through the input interface 110 in the storage 130. In one embodiment, the image processing unit 120 may be further configured to display a user interface screen displaying a rendered image of a 3D X-ray image of the head of the human body and a cross-sectional image of the 3D image in an axial direction on the display unit 140, and to provide various utility functions that allow a user to conveniently and easily select a 3D region of interest and an arbitrary point by referring to the user interface screen. The image processing unit 120 may be further configured to define a curved plane that substantially separates the condylar region and the glenoid region based on the horizontal or vertical coordinates of an arbitrary point designated by the user.

In various embodiments, the image processing unit 120 may be configured to define a standard line, for example, a standard curve, for each of the cross-sectional images of the 3D region of interest. Here, one point of the standard curve may have a horizontal or vertical coordinate value that is the same as a horizontal or vertical coordinate value of an arbitrary point input by a user through the input interface 110 or within a range selected therefrom. In various embodiments, the image processing unit 120 may be further configured to generate a separation curve by adjusting a position of a point of the standard curve and/or a width of the standard curve so that the points of the standard curve are located in the gap between the condylar region and the glenoid region.

The image processing unit 120 may be configured to generate a binarized cross-sectional image by binarizing each cross-sectional image of the 3D region of interest. The image processing unit 120 may be configured to move the position of one point of the standard curve in the vertical or horizontal direction so that the position of one point of the standard curve defined for each cross-sectional image of the 3D region of interest is located in the gap between the condylar region and the glenoid region. In various embodiments, the image processing unit 120 may be further configured to adjust the height of one point of the standard curve based on a change in the luminance value of a pixel in the binarized cross-sectional image corresponding to one point, which is generated as one point of the standard curve is moved in a vertical or horizontal direction, and/or a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points on the standard curve.

The image processing unit 120 may be configured to adjust the width of the standard curve so that the standard curve more closely covers the condyle area. In various embodiments, the image processing unit 120 may be configured to adjust the width of the standard curve so that the sum of luminance values of pixels in the binarized cross-sectional image corresponding to the points of the standard curve is minimized. In various embodiments, the image processing unit 120 may be further configured to construct a set of separation points by moving at least one of the points of the standard curve in a vertical or horizontal direction so that the points of the standard curve are located in the gap between the condylar region and the glenoid region, and correct the set of separation points to generate a separation curve.

The image processing unit 120 may be further configured to define a curved surface that substantially separates the condylar region and the glenoid region using the generated separation curves. The image processing unit 120 may be further configured to perform 2-dimensional smoothing filtering on a curved surface formed by the separation curves. The image processing unit 120 may be further configured to separate the condylar region from the glenoid region and display the condyle area on the display unit 140 by referring to the defined curved surface.

In terms of hardware, the image processing unit 120 includes application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, and micro-controllers. s) and microprocessors. The image processing unit 120 may also be implemented as a firmware/software module executable on the aforementioned hardware platform. In this case, the firmware/software module may be implemented by one or more software applications written in an appropriate program language.

FIG. 2 is a flowchart illustrating an embodiment of a method of separating a condyle area of a joint and a glenoid area of a joint in a 3D X-ray image according to the present invention. 3 is a diagram schematically illustrating a method of designating a 3D region of interest in a 3D X-ray image according to an embodiment of the present invention. 4 is a diagram showing a photograph illustrating a cross section of a 3D region of interest selected from a 3D X-ray image according to an embodiment of the present invention. 5 is a diagram showing a photograph illustrating a cross section of another 3D region of interest selected from a 3D X-ray image according to an embodiment of the present invention. FIG. 6 is a diagram illustrating an example of a user interface screen provided on a display unit by the device of FIG. 1 to allow a user to select a reference point and a 3D region of interest in a 3D X-ray image. FIG. 7 is a diagram showing a picture of an embodiment of a binarized cross-sectional image of a 3D region of interest, and is a diagram for explaining how a standard curve is defined based on reference points designated by a user with respect to the cross-sectional image. 8 is a diagram showing a picture of an embodiment of a binarized cross-sectional image of a 3D region of interest in which a point of a standard curve, for example, a vertex is moved to a gap between the condylar region and the glenoid region. 9 is a diagram showing a picture of an embodiment of a binarized cross-sectional image of a 3D region of interest in which the width of a standard curve is adjusted. 10 is a diagram showing a photograph of an embodiment of an image in which only the condylar region is separated and displayed. Hereinafter, an embodiment of a method for separating the condylar region of a joint and the glenoid region of a joint in a 3D X-ray image according to the present invention will be described with reference to FIGS. 2 to 10 . However, hereinafter, an embodiment of the present method will be described by taking the condylar region and the glenoid region of the temporomandibular joint of a human body as examples of the condylar region and glenoid region of the joint. In addition, in the following description, it is assumed that the voxel data of the 3D X-ray image is structured so that the sectional image (sagittal view) of the left or right side of the patient's face in the 3D X-ray image is aligned on the X-Y plane as shown in FIG.

Referring to FIG. 2 , one embodiment of the method begins with receiving a user input designating a 3D region of interest (ROI) including the region of the temporomandibular joint in a 3D X-ray image (S210). In this step, the user may designate a cuboid or cube-shaped subspace including the temporomandibular joint in the 3D X-ray image using the input interface 110 as shown in FIG. 3 . In one embodiment, an arbitrary sectional image of a 3D X-ray image may be displayed on the display unit 140 so that a user can designate a subspace. In this case, the arbitrary sectional image may be, for example, a sagittal sectional image as shown in FIG. 4 or an axial view as shown in FIG. 5 . In one embodiment, the cross-sectional image in the sagittal direction and the cross-sectional image in the axial direction can be displayed on the display unit 140 using Multi-Planar Reconstruction (MPR).

In one embodiment, while referring to the cross-sectional image in the sagittal direction of FIG. 4 displayed on the display unit 140, the user inputs the coordinates (X ₁ , X ₂ ) of the end points of the segment ΔX in the horizontal direction, the coordinates (Y ₁ , Y ₂ ) of the end points of the segment ΔY in the vertical direction, and the coordinates (Z ₁ , Z ₂ ) of the end points of the segment ΔZ in the depth direction to be specified as shown in FIG. 3 through an input interface ( 110), it is possible to designate a subspace in a 3D X-ray image. In another embodiment, if the user inputs only the coordinates (X ₁ , X ₂ ) of the end points of the segment ΔX in the horizontal direction and the coordinates (Y ₁ , Y ₂ ) of the end points of the segment ΔY in the vertical direction, the coordinates (Z ₁ , Z ₂ ) of the end points of the segment ΔZ in the depth direction may be automatically designated as default values. In another embodiment, instead of having the user directly input the coordinates of the end points of the segments as described above, the subspace may be designated by allowing the user to click and drag a vertex of a rectangle on the XY plane to be designated in the cross-sectional image in the sagittal direction displayed on the display unit 140 and drag it to the vertex on the diagonal side while automatically designating the segment ΔZ in the depth direction.

It is possible to designate a subspace in a similar manner while referring to the cross-sectional image in the axial direction shown in FIG. 5 . In this case, the cross-sectional image in the axial direction may be a cross-sectional image in which the cross-section of the condyle is reflected, as shown in FIG. 5 . In one embodiment, while referring to the cross-sectional image in the axial direction of FIG. 5 displayed on the display unit 140, the user inputs the coordinates (X ₁ , X ₂ ) of the end points of the segment ΔX in the horizontal direction, the coordinates (Y ₁ , Y ₂ ) of the end points of the segment ΔY in the vertical direction, and the coordinates (Z ₁ , Z ₂ ) of the end points of the segment ΔZ in the depth direction to be specified as shown in FIG. 3 through an input interface. By inputting using (110), a subspace in a 3D X-ray image can be specified. In another embodiment, if the user inputs only the coordinates (X ₁ , X ₂ ) of the end points of the segment ΔX in the horizontal direction and the coordinates (Z ₁ , Z ₂ ) of the end points of the segment ΔZ in the depth direction, the coordinates (Y ₁ , Y ₂ ) of the end points of the segment ΔY in the vertical direction may be automatically assigned as default values. In another embodiment, instead of having the user directly input the coordinates of the end points of the segments as described above, the subspace may be designated by allowing the user to click and drag the vertex of the rectangle on the XZ plane to be designated in the cross-sectional image in the axial direction displayed on the display unit 140 and drag it to the diagonal vertex while automatically designating the segment ΔY in the vertical direction.

The designated subspace is composed of a set of voxels composed of pixel values at pixel positions of the 3D X-ray image partitioned by the designated coordinates as described above, and information about them is stored in the storage unit 130 under the control of the image processing unit 120. Sections of a 3D region of interest (ROI) selected from a 3D X-ray image according to an embodiment of the present invention are illustrated in FIGS. 4 and 5 .

Next, in step S220, a user input designating an arbitrary point in the condyle region within the 3D region of interest designated in step S210 is received (hereinafter, the aforementioned arbitrary point will be referred to as a 'reference point'). In various embodiments, this step may include displaying a sectional image of the designated 3D region of interest on the display unit 140 . In one embodiment, the cross-sectional image may be a cross-sectional image in a sagittal direction or a cross-sectional image in an axial direction, as in step S210. In another embodiment, when the user designates a 3D region of interest while referring to a sectional image in the sagittal direction in step S210, the cross sectional image may be a cross sectional image in the sagittal direction of the 3D region of interest. When the cross-sectional image of the 3D region of interest in the sagittal direction or the cross-sectional image in the axial direction of the 3D region of interest is displayed on the display unit 140, the user may designate the aforementioned reference point while referring to them.

In the embodiment described above, it has been described that a 3D region of interest is designated in the 3D X-ray image in step S210 and then a reference point in the condyle region is designated in the 3D region of interest in step S220. However, if the user designates a reference point in the condyle region while referring to a cross-sectional image in the sagittal direction of the 3D X-ray image or a cross-sectional image in the axial direction in which the cross-section of the condyle is reflected, a certain region is set as a 3D region of interest based on the designated reference point. It is possible. In one embodiment, the 3D region of interest may be set as a default to have a volume of 1 x 1 x 1 inch or 2 x 2 x 2 inches centered on a designated reference point. In one embodiment, various options regarding the size of the 3D region of interest may be provided to the user and the user may be allowed to select a desired size. In one embodiment, it is also possible to automatically set a 3D region of interest based on a designated reference point according to the size of the 3D region including the temporomandibular joint.

Now, with reference to FIG. 6 showing an embodiment of the user interface screen provided to the display unit 140 by the device of FIG. 1, the user selects a 3D region of interest and a reference point in the 3D X-ray image. Other embodiments of steps S210 and S220 will be described. In FIG. 6, the first picture from the left is a picture 610 of an image rendered by rendering a three-dimensional X-ray image of the head of the human body in the front direction, and the second picture is a picture 620 of an image rendered by rendering the same image in the left direction. The third picture is an axial cross-sectional image of the same three-dimensional X-ray image, which shows a picture 630 of a cross-sectional image in which the cross section of the condyle of the temporomandibular joint is reflected.

The user refers to the user interface screen shown in FIG. 6 and utilizes at least one of the following utility functions provided by the input interface 110 and the image processing unit 120 to set a 3D region of interest and a reference point in the 3D X-ray image.

A function to set the upper boundary of the region of interest ( ROI upper boundary locator)

The user may set the upper boundary of the ROI by moving the solid line 617 displayed in the picture 610 up and down using a mouse or the like while referring to the picture 610 and the picture 620 . In one embodiment, a region in the photo 610 and/or the photo 620 selected by the upper boundary and the lower boundary described later may be displayed brighter than the surrounding region. In order to provide convenience in setting the upper boundary, when the user adjusts the position of the solid line 617 by moving the solid line 617 up and down in the photo 610, the position of the solid line 627 can be adjusted to correspond to the same display of the upper boundary in the photo 620.

The function of setting the lower boundary of the region of interest ( ROI upper boundary locator)

The user may set the lower boundary of the region of interest by moving the solid line 618 displayed in the photo 610 up and down using a mouse or the like while referring to the photo 610 and the photo 620 . Similarly to the case of setting the upper boundary, in order to provide convenience in setting the lower boundary, if the user moves the solid line 618 up and down in the picture 610 to adjust the position of the solid line 618, the position of the solid line 628 can be adjusted to correspond to display the lower boundary in the same way in the picture 620.

Axial Reference point setting function in sectional image of direction

A user may select any one cross-sectional image among several cross-sectional images in the axial direction using a mouse or the like. In selecting one of the cross-sectional images in the axial direction, it is possible to select any one cross-sectional image in which the cross-section of the condyle of the temporomandibular joint is reflected. A photograph of an illustratively selected cross-sectional image is indicated at 630 in FIG. 6 . When a cross-sectional image is selected, positions of corresponding cross-sections in the picture 610 and the picture 620 may be displayed as a dotted line 615 and a dotted line 625 inside the region ROI selected by the upper boundary and the lower boundary, respectively. In addition, while referring to the photo 630 of the selected cross-sectional image in the axial direction, the user can move at least one of the blocks 632 and 633 (axial point locators) of two crosses (+) displayed overlaid on the same photo 630 up, down, left, and right so that the center point of the cross mark is arranged at the position of the condyle to be selected as a reference point. In one embodiment, the two cross-shaped blocks 632 and 633 can be moved separately to select different reference points for the left and right condyles. In this case, it is also possible to separate the condylar region and the glenoid region for both the left and right joints by separately performing steps (S230) to (S280) described below based on each of the two reference points.

Area of interest size setting function ( ROI size set)

A mark 'Vertical' at the bottom of the picture 630 indicates a vertical direction in the axial sectional image of the picture 630, and a mark 'Horizontal' indicates a horizontal direction in the axial sectional image of the picture 630. The menu button 635 immediately below the mark 'Vertical' is for adjusting the length in the vertical direction of the blocks 632 and 633 of the cross marks overlaid on the photo 630. When the menu button 635 is clicked, various lengths are displayed, and among them, one length can be selected according to the size of the 3D X-ray image or the area the user wants to see. In the illustrated embodiment, the longitudinal length is chosen to be 40 mm. Similarly, the menu button 637 immediately below the mark 'Horizontal' is for adjusting the horizontal length of the blocks 632 and 633 of the cross marks overlaid on the photo 630. When the menu button 637 is clicked, various lengths are displayed, and among them, one length can be selected according to the size of the 3D X-ray image or the region the user wants to see. In the illustrated embodiment, the transverse length is chosen to be 55 mm. When the length in the vertical direction and the length in the horizontal direction are selected using the menu buttons 635 and 637, the length in the vertical direction and the horizontal direction of the blocks 632 and 633 of the cross marks are adjusted accordingly and displayed as shown.

As shown in FIG. 7, the reference point designated as above is defined as a horizontal coordinate (X _p ) and a vertical coordinate (Y _p ) in a 3-dimensional X-ray image or a 3-dimensional region of interest.

Returning to the description of FIG. 2 again, in step S230, a standard line, for example, a standard curve, is defined for each of the cross-sectional images of the 3D region of interest. In one embodiment, cross-sectional images in this case may be cross-sectional images in a sagittal direction. In an embodiment, a standard curve may be sequentially defined for cross-sectional images before and after the cross-sectional image including the reference point. As the standard curve, an arbitrary curve having a shape similar to the condyle of the temporomandibular joint when the patient's face is observed from the left or right side can be selected. In one embodiment, the standard curve may be chosen as a curve that can be expressed as a mathematical function to conveniently identify the location of every point on the curve. In one embodiment, the standard curve may be a normal distribution curve represented by Equation (1) below.

수학식 (1)

Equation (1)

는 단계(S220)에서 사용자에 의해 지정된 기준점의 수평 좌표(X_p), 즉 3차원 관심 영역에서 곡선의 정점이 위치하게 될 수평 좌표에 해당하고(도 7 참조),

는 곡선의 너비를 조정하기 위한 변수, 즉 곡선의 정점으로부터 아래쪽으로 커버하는 넓이를 조정하기 위한 변수이고,

는

의 값이 결정됨에 따라 결정되는 값으로 곡선의 높이를 나타내는 값이다. 본 개시에 있어서,

를 편의상 상수 값인

로 칭한다. 표준 곡선으로서, 앞서 예시된 정규 분포 곡선 이외에도 레이라이 분포(Rayleigh distribution) 곡선 또는 상승 코사인(raised cosine) 함수 등 턱관절의 관절구와 유사한 모양을 갖는 어떠한 임의의 곡선도 선택할 수 있으며, 따라서 표준 곡선으로 선택 가능한 곡선이 본 개시에서 예시된 곡선들에 한정되는 것이 아님을 인식하여야 한다.In Equation (1),

Corresponds to the horizontal coordinate (X _p ) of the reference point specified by the user in step S220, that is, the horizontal coordinate where the apex of the curve will be located in the 3-dimensional region of interest (see FIG. 7),

Is a variable for adjusting the width of the curve, that is, a variable for adjusting the area covered downward from the vertex of the curve,

Is

It is a value that is determined according to the value of is determined and represents the height of the curve. In this disclosure,

which is a constant value for convenience

is called As the standard curve, in addition to the normal distribution curve exemplified above, any arbitrary curve having a shape similar to the condyle of the temporomandibular joint, such as a Rayleigh distribution curve or a raised cosine function, can be selected. Accordingly, it should be recognized that the curves selectable as the standard curve are not limited to the curves exemplified in the present disclosure.

As shown in FIG. 7 , the selected standard curve is defined as a curve that extends left and right in a downward direction centered on the vertex with the coordinates (X _p , Y _P ) of the reference point designated by the user in the cross-sectional image of the 3D region of interest as the coordinates of the vertex. When a standard curve is defined for an arbitrary cross-sectional image, a standard curve is sequentially defined for cross-sectional images before and after the arbitrary cross-sectional image (in the case of a cross-sectional image in a sagittal direction, in a depth direction). In one embodiment, it is possible to select and define the same standard curve for each cross-sectional image. In another embodiment, it is also possible to select and define different standard curves for at least some cross-sectional images. In the present disclosure, the meaning that a standard curve is defined for a cross-sectional image may mean that the standard curve is superimposed on the cross-sectional image and displayed, but it can be understood mainly as meaning that the positions of pixels corresponding to coordinates of points constituting the standard curve among the positions of pixels of the cross-sectional image are stored in the storage unit 130 under the control of the image processing unit 120.

In step S240, binarized cross-sectional images are generated by binarizing cross-sectional images of the 3D region of interest. In an embodiment, each cross-sectional image may be binarized by performing a thresholding process on each cross-sectional image based on a minimum luminance value among luminance values of pixels representing a region corresponding to a facial skeleton in each cross-sectional image of the 3D region of interest. The reason for binarizing each cross-sectional image is to make a hard decision on whether the corresponding point is still located on a bone or moved to a gap between bones when each of the points forming the standard curve is moved. An example of a binarized cross-sectional image is shown in FIG. 7 . In one embodiment, it is also possible to omit this step.

In step S250, a separation curve may be generated for a corresponding cross-sectional image by adjusting a standard curve defined for each cross-sectional image. In this step, the position of the vertex of the standard curve defined for each cross-sectional image may be moved in the vertical direction so that the position of the vertex of the standard curve is located in the gap between the condylar region and the glenoid region. In an embodiment, the height of a vertex of the standard curve may be adjusted based on a change in the luminance value of a pixel in the binarized cross-sectional image corresponding to the vertex and/or a sum of luminance values of pixels in the binarized cross-sectional image corresponding to the points of the standard curve, which are generated as the vertex of the standard curve is moved in the vertical direction. For example, by moving the vertex of the standard curve upward, the luminance value of the pixel corresponding to the vertex is reduced compared to before the movement (e.g., from 1 to 0), but if the sum of the above-mentioned luminance values does not decrease or becomes larger, it can be determined that the vertex of the standard curve has not yet moved to the gap between the condyle area and the joint fossa area. On the other hand, if the luminance value of the pixel corresponding to the vertex is reduced compared to before the movement by moving the vertex of the standard curve upward, and the sum of the above-mentioned luminance values is also reduced at the same time, it can be determined that the apex of the standard curve has moved to the gap between the condyle area and the joint fossa area. A photograph of an embodiment of a binarized cross-sectional image of a 3D region of interest in which the apex of the standard curve is moved to the gap between the condylar region and the glenoid region is shown in FIG. 8 .

In this step, the position of the apex of the standard curve may be selectively moved within a predetermined range in the horizontal direction. This is to allow the standard curve to more closely cover the condyle area downward, under the assumption that an arbitrary point designated by the user's eye may not necessarily be ideal. In one embodiment, the sum of luminance values of pixels in the binarized cross-sectional image corresponding to the points of the standard curve may be used as a criterion for moving the vertex of the standard curve in the horizontal direction.

값을 이용하여 표준 곡선의 너비를 조정할 수 있다. 일 실시예에서, 표준 곡선의 점들에 해당하는 이진화 단면 영상에서의 픽셀들의 휘도 값들의 합이 최소가 되도록 표준 곡선의 너비를 조정할 수 있다. 표준 곡선의 너비가 조정된 3차원 관심 영역의 이진화된 단면 영상의 일 실시예의 사진이 도 9에 도시되어 있다.At this stage, the width of the standard curve can be adjusted so that the standard curve more closely covers the condylar area downwards. For example, when using a normal distribution curve as a standard curve,

The value can be used to adjust the width of the standard curve. In an embodiment, the width of the standard curve may be adjusted such that the sum of luminance values of pixels in the binarized cross-sectional image corresponding to the points of the standard curve is minimized. A picture of an embodiment of a binarized cross-sectional image of a 3D region of interest in which the width of the standard curve is adjusted is shown in FIG. 9 .

In addition, in this step, a set of separation points may be configured by moving at least one of the points of the standard curve in the vertical direction so that the points of the standard curve are located in the gap between the condylar region and the glenoid region. In one embodiment, the corresponding point may be moved in the vertical direction based on the change in the luminance value of the pixel in the binarized cross-sectional image corresponding to the corresponding point, which is generated when each point constituting the standard curve is moved in the vertical direction. For example, if a luminance value of a pixel corresponding to the point is reduced compared to before the movement when a point on the standard curve is moved upward, the moved location may be determined as the split point. In some cases, some of the separation points determined by moving the points of the standard curve in the vertical direction may not be located in the gap between the condyle area and the glenoid area due to processing errors, and accordingly, height deviation may occur between the separation points. In this case, the height of the separation point having a height deviation may be corrected by matching the height of the separation point with a height close to the height of the horizontally adjacent separation points. In one embodiment, the correction of the separation point having a height deviation may be performed by discarding the separation point and interpolating the heights of the separation points horizontally adjacent to the separation point. In one embodiment, it is also possible to perform the above-described processing on a width-adjusted standard curve.

As described above, it is possible to generate a separation curve for each cross-sectional image of a 3D region of interest by moving the vertex of the standard curve in vertical/horizontal directions, adjusting the width of the standard curve, or individually moving each point of the standard curve or the standard curve having the adjusted width upward and downward to form a set of separation points. It should be appreciated that one or more of the adjustment options described above may be employed in generating each separation curve.

In the above description, each of steps S230 to S250 has been described as being performed on cross-sectional images of the 3D region of interest, but depending on implementation, steps S230 to S250 may be performed on each cross-sectional image of the 3D region of interest.

In step S260, a curved surface that substantially separates the condylar region and the glenoid region in the 3D region of interest is defined using the separation curves generated in step S250. Since the meaning of 'defining' is as described in relation to step S230, its description is omitted here. In addition, in the present disclosure, the meaning of 'substantially separating' should be understood to include not only the meaning of ideally separating the condylar region and the glenoid region, but also the meaning of substantially accurately separating the condylar region and the glenoid region within a certain range of error. Vertices of the separation curves forming the curved surface generated in this step have the same horizontal coordinates as the horizontal coordinates of an arbitrary point designated by the user in step S220 or within a range selected therefrom. Therefore, it should be understood that the curved surface created in this step is defined based on the horizontal coordinates of an arbitrary point designated by the user in step S220 or the horizontal coordinates within a range selected therefrom.

In step S270, 2-dimensional smoothing filtering may be performed on the curved surface generated in step S260. The curved surface created in step S260 may be bumpy or deviated depending on circumstances. Accordingly, the curved surface can be made gentle and smooth by performing two-dimensional flattening filtering on the curved surface. In one embodiment, the two-dimensional smoothing filtering may be performed using a Gaussian smoothing filter defined by Equation (2) below.

수학식 (2)

Equation (2)

In the present disclosure, the Gaussian flattening filter is used as an example in performing the two-dimensional flattening filtering on the curved surface, but it should be recognized that various other two-dimensional filters may be used.

In step S280, referring to the curved surface generated in step S260 or the curved surface generated by filtering the curved surface in step S270, the condylar region may be separated from the glenoid region and displayed on the display unit 140. In one embodiment, only the separated condyle area or only the separated condyle area may be rendered and displayed on the display unit 140 in a three-dimensional manner. In one embodiment, the separated condylar region or glenoid region can be rotated and moved in three dimensions so that wear or deformation of the contact portion can be observed. 10 shows a picture of an example of an image in which only the condylar region is separated and displayed.

In the embodiments disclosed herein, the arrangement of the illustrated components may vary depending on the environment or requirements in which the invention is implemented. For example, some components may be omitted or some components may be integrated and implemented as one. In addition, the arrangement order and connection of some components may be changed.

Although various embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the above-described embodiments can be variously modified and implemented by those skilled in the art without departing from the gist of the present invention claimed in the appended claims, and these modified embodiments should not be understood separately from the technical spirit or scope of the present invention. Therefore, the technical scope of the present invention should be defined only by the appended claims.

110: input interface
120: image processing unit
130: storage unit
140: display unit

Claims (18)

delete delete delete delete delete delete delete delete delete A method of separating a condylar region of a joint and a condyle region of the joint in a three-dimensional X-ray image, comprising:
Receiving a user input designating a reference point within the condyle area in the 3-dimensional X-ray image; and
Defining a curved surface substantially separating the condylar area and the glenoid area based on the horizontal or vertical coordinates of the designated reference point;
Defining a curved surface that substantially separates the condyle region and the glenoid region based on the horizontal or vertical coordinates of the designated reference point
For each of the cross-sectional images of the 3-dimensional X-ray image, defining a standard curve, wherein one point of the standard curve has a horizontal or vertical coordinate value equal to or within a range selected from the horizontal or vertical coordinate value, and generating a separation curve by adjusting the height and/or the width of the standard curve so that the points of the standard curve are located in the gap between the condyle area and the joint area, and
defining the curved surface using the generated separation curves. delete A method of separating a condylar region of a joint and a condyle region of the joint in a three-dimensional X-ray image, comprising:
Receiving a user input designating a reference point within the condyle area in the 3-dimensional X-ray image; and
Defining a curved surface substantially separating the condylar area and the glenoid area based on the horizontal or vertical coordinates of the designated reference point;
Wherein the joint comprises a temporomandibular joint of a human body. A method of separating a condylar region of a joint and a condyle region of the joint in a three-dimensional X-ray image, comprising:
Receiving a user input designating a reference point within the condyle area in the 3-dimensional X-ray image; and
Defining a curved surface substantially separating the condylar area and the glenoid area based on the horizontal or vertical coordinates of the designated reference point;
Defining a curved surface that substantially separates the condyle region and the glenoid region based on the horizontal or vertical coordinates of the designated reference point
Defining a standard curve for each of the cross-sectional images of the 3D X-ray image, wherein one point of the standard curve has a horizontal or vertical coordinate value equal to or within a range selected from the horizontal or vertical coordinate value, constructing a set of separation points by vertically or horizontally moving at least one point of the standard curve so that the points of the standard curve are located in the gap between the condyle area and the joint area, and correcting the set of separation points to generate a separation curve. step of doing, and
defining the curved surface using the generated separation curves. According to claim 10,
Generating a separation curve by adjusting the height of the one point of the standard curve and / or the width of the standard curve so that the points of the standard curve are located in the gap between the condyle region and the glenoid region
Generating a binarized cross-sectional image by binarizing each of the cross-sectional images of the 3-dimensional X-ray image, and
Adjusting the height of the one point of the standard curve based on a change in the luminance value of a pixel in the binarized cross-sectional image corresponding to the one point and / or a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points of the standard curve, which are generated as the one point of the standard curve is moved in a vertical or horizontal direction. According to claim 10,
Generating a separation curve by adjusting the height of the one point of the standard curve and / or the width of the standard curve so that the points of the standard curve are located in the gap between the condyle region and the glenoid region
Generating a binarized cross-sectional image by binarizing each of the cross-sectional images of the 3-dimensional X-ray image, and
And adjusting a width of the standard curve such that a sum of luminance values of pixels in the binarized cross-sectional image corresponding to points of the standard curve is minimized. delete The method of claim 10, 12 or 13,
The method further comprising the step of separating the condylar region from the glenoid region by referring to the curved surface and displaying the condyle region on a display. The method of claim 10, 12 or 13,
The method further comprising receiving a user input designating a 3D region of interest including the region of the joint in the 3D X-ray image.

Images