JP2006021016A - Three-dimensional tomographic image creation method and computer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accurate three-dimensional CT image of upper and lower jaw bones and upper and lower dentitions by removing artifacts caused by a metal restoration or the like.
A method of creating a three-dimensional tomographic image of an oral cavity region having an artifact source includes a step of inputting oral region tomographic data and dentition model tomographic data to a computer via an input means; A step of creating a three-dimensional oral region image including a marker from the tomographic data and displaying it on the display means, and a step of creating a three-dimensional dental model image including the marker from the dentition model tomographic data, The displaying step and the calculation means are configured to display the three-dimensional oral region image and the three-dimensional dental model image so that the marker in the three-dimensional oral region image and the marker in the three-dimensional dental model image substantially coincide with each other. Overlay, trim 3D dentition model image, delete artifacts contained in 3D oral area image, replace 3D oral area image with 3D dentition model image, 3D image Tomographic images and Including the step of.
[Selection] Figure 6

Description

  The present invention relates to a method and computer system for creating a three-dimensional tomographic image, and more particularly, to a method and computer system for creating a three-dimensional tomographic image of the maxilla and mandibular bone and upper and lower dentition from which the artifact of the tomographic image has been removed. .

It is important to grasp the shape of the upper and lower jaw bones and upper and lower dentitions in an artificial root implant operation or the like in dentistry. For this reason, conventionally, a CT (Computerized Tomography) image of the oral cavity region was taken, and a three-dimensional CT image of the upper and lower jaw bones and upper and lower dentition was obtained based on the CT image (for example, Non-Patent Documents 1 and 2). ).
Aita, H., Ueda, Y., Tamura, S., Kasai, N., Ohata, N., Inoue, N., Kobayashi, H. & Ikeda, K. (2002) "A new method of removing metal artifacts from 3-D model data for rapid prototyping ", Maxillofacial Prosthetics 25: pp42 G Goerres, GW, Hany, TF, Kamel, E., von Schulthess, GK & Buck, A. (2002) "Head and neck imaging with PET and PET / CT: artefacts from dental metallic implants", European Journal of Nuclear Medicine and Molecular Imaging 29: pp367-370

  However, when there is a dental metal restoration in the oral cavity, artifacts (image defects) due to the dental metal restoration occurred in the CT image. For this reason, the three-dimensional CT images of the upper and lower jaw bones and upper and lower dentitions created by synthesizing the two-dimensional CT images are not accurately displayed, and the removal of artifacts has been demanded.

  On the other hand, an attempt has been made to erase artifacts by image processing of a two-dimensional CT image. However, when the artifacts are large and, for example, most of the dentition is covered with the artifacts, only the artifacts are removed. It was impossible.

  On the other hand, in an artificial root implant operation or the like, a dentition model is usually made of plaster or the like. The inventors focused on such a dentition model and found that a three-dimensional CT image from which artifacts have been removed can be obtained by correcting the patient's three-dimensional CT image using the shape data of the dentition model. The present invention has been completed.

  That is, an object of the present invention is to remove an artifact caused by a metal restoration or the like and obtain an accurate three-dimensional tomographic image of the maxilla and mandible or the upper and lower teeth.

The present invention is a method for creating a three-dimensional tomographic image of an oral cavity region having an artifact source using a computer including an input unit, a display unit, and a calculation unit,
(A) a step of inputting oral region tomography data obtained by tomographic imaging of a patient's oral region to a computer via an input means while biting an interface bite including a bite and a marker;
(B) inputting tomographic model tomographic data obtained by tomographic imaging of a state in which the patient's dental model bites the bite;
(C) creating a three-dimensional oral region image including a marker from oral region tomography data and displaying it on the display means;
(D) creating a three-dimensional dentition model image including a marker from the dentition model tomography data and displaying it on the display means;
(E) The computing means is
Superimposing the 3D oral region image and the 3D dentition model image so that the marker in the 3D oral region image and the marker in the 3D dentition model image substantially match,
Trimming the three-dimensional dentition model image based on the selected area selected via the input means,
Based on the selected area selected via the input means, the artifacts included in the 3D oral area image are deleted,
And a step of replacing a part of the three-dimensional oral region image with a three-dimensional dentition model image and combining the resultant image with the three-dimensional tomographic image.

The present invention also provides a computer system for creating a three-dimensional tomographic image of an oral cavity region having an artifact source,
Input means for inputting the oral region tomography data of the patient and the dentition model tomography data of the patient's dentition model;
Display means for displaying a three-dimensional oral region image created from oral region tomography data and a three-dimensional dental model image created from dental model tomography data;
At the position where the two images are superimposed so that the reference point in the three-dimensional oral region image and the reference point in the three-dimensional dental model image substantially coincide, a part of the three-dimensional oral region image is converted into the three-dimensional dental row Means to replace the model image and compose the image;
Trimming means for trimming a three-dimensional dentition model image based on a selection region input via the input means;
It is also a computer system characterized by including removal means for removing artifacts included in the three-dimensional oral cavity region image based on the selected region input via the input means.

  By using the three-dimensional tomographic image creation method and creation computer system according to the present invention, accurate three-dimensional tomographic images of the maxilla and maxillary dentition can be obtained, leading to clinical examples such as artificial root implant surgery. Can be applied.

  FIG. 1 is an intraoral photograph (mandible) of a patient having a dental metal restoration. FIG. 2 shows a three-dimensional oral region image obtained by taking a CT image of the oral region of a patient having such a metal restoration and synthesizing it into a three-dimensional image. The three-dimensional oral region image is synthesized by stacking CT images that are tomographic images. A haptic device (trade name: PHANToM) is used for the synthesis of the three-dimensional oral region image.

  As shown in FIG. 2, when a patient has a metal restoration, an artifact (image failure) due to the metal restoration occurs, and an accurate image of the dentition portion cannot be obtained. For example, for CT imaging of the maxilla and mandible, high-density gold alloy, silver alloy, Ni—Cr alloy, Co—Cr alloy, stainless steel, etc. are artifact sources that generate artifacts.

  On the other hand, when an artificial root implant operation or jaw deformity operation is performed, a plaster dentition model is usually produced. Since the dentition model is made by taking a mold of the patient's dentition, the dentition of the patient is accurately reproduced.

  In the present embodiment, a three-dimensional dentition model image is taken from the dentition model, and a part of the three-dimensional oral region image is replaced using the three-dimensional dentition model image.

FIG. 3 shows an interface serving as a reference for positioning when a part of a three-dimensional oral region image of a patient is replaced with a three-dimensional dentition model image. The interface represented as a whole by 10 is composed of a dentition bit 1 and an alignment marker plate 2.
The dentition bite 1 has a shape corresponding to the dentition of the patient. Further, the dentition bite 1 is formed of a material that is not photographed with CT values (400 to 900) used for photographing the jawbone and the dentition model. Examples of such materials include polymer materials (immediate polymerization resin) such as polymethyl methacrylate (PMMA), and rubber-based materials such as silicone, urethane, and thiocol. The marker plate 2 is made of a plate-like body made of gypsum. For example, a circular convex portion (or concave portion) having a diameter of 4 to 5 mm is partially provided on the surface of the marker plate 2. In the alignment process described later, the alignment accuracy is improved by aligning such convex portions.

Here, first, a three-dimensional tomographic image creation method according to the present embodiment will be described with reference to the flowchart of FIG. CT imaging is imaging of the jawbone and dentition model, which is performed using CT values used for imaging of the jawbone and dentition model.
In this method, first, the patient's dentition model 20 is made of, for example, plaster. This plaster model is a model used in general dental treatment.

  Next, as shown in FIG. 4A, the interface 10 is bitten by the dentition model 20. As described above, the dental cutting tool 1 of the interface 10 is configured to mesh with the dental model 20.

In this way, a CT image (dental model tomography data) is acquired in a state where the interface 10 is engaged with the dental model 20 and fixed. A 16-row multi-slice helical CT (SOMATOM Sensation 16, manufactured by Siemens, slice width: 0.31 mm) is used for taking a CT image. The CT image is input to the computer via the input means and stored in the storage means as DICOM data (step S11).
Further, a three-dimensional dental model image is constructed using the obtained CT image (dental model tomography data). The construction of the three-dimensional dentition model image is performed using, for example, VGStudio MAX1.1 (manufactured by Volume Graphic), and DICOM data is converted into three-dimensional data in the STL (Standard Template Library) format and displayed. Or the like (step S12).

  FIG. 4B shows a three-dimensional dentition model image 25 in a state where the interface 10 is bitten by the dentition model 20 displayed on the display means. As described above, a dental cutting tool made of an immediate polymerization resin or the like is not shown in a CT image.

  Next, as shown in FIG. 5A, the oral cavity region is imaged with the patient 10 biting the interface 10, and a CT image (oral region tomographic data) is obtained. Such data is input to the computer via the input means and stored in the storage means (step S21).

  Oral area tomography data is combined with the three-dimensional oral area image 35 and displayed on the display means (step S22). FIG. 5B is a three-dimensional oral region image 35 in a state where the patient 10 bites the interface 10. As can be seen from FIG. 5B, artifacts are generated near the dentition due to the influence of the metal restoration. Further, the dentition bite is not shown in the three-dimensional oral region image 35.

  Next, as shown in FIG. 6, the three-dimensional dentition model image 25 of FIG. 4B and the three-dimensional oral cavity region image 35 of FIG. Specifically, the three-dimensional dentition model image 25 in FIG. 4B is placed on the coordinates of the three-dimensional oral region image 35 in FIG. 25, a part of the three-dimensional oral region image 35 is replaced and a three-dimensional image is synthesized (step S3).

  When replacing a three-dimensional image, alignment is performed so that the marker plates 2 in both three-dimensional images overlap. Use Polygon Edition Tool (Konica-Minolta) for alignment. By synthesizing the CT image using a reference such as the marker plate 2, the three-dimensional dental model image 25 can be taken into the three-dimensional oral region image 35 with high positional accuracy.

Specifically, first, reference points (three points) on the marker plate 2 included in the three-dimensional dentition model image 25 are extracted. Next, for the marker plate 2 included in the three-dimensional oral cavity region image 35, reference points (three points) at the same position on the marker plate 2 are extracted.
Here, since the same marker plate 2 is used in both three-dimensional images, the position of the reference point is accurately extracted. In addition, since the convex portion is provided on the surface of the marker plate 2, the reference point can be easily and accurately specified.
It is also possible to use different markers in both three-dimensional images. Further, alignment may be performed using a specific tooth or a tooth wound as a reference point.

  Next, the three points extracted on the marker plate 2 included in the three-dimensional dental model image 25 overlap the three points extracted on the marker plate 2 included in the three-dimensional oral region image 35. The three-dimensional oral region image 35 and the three-dimensional dentition model image 25 are superimposed. In this process, the three-dimensional oral cavity region image 35 and the three-dimensional dentition model image 25 are approximately aligned.

  Subsequently, for example, a normal vector method is applied to the marker plate 2 included in the three-dimensional dentition model image 25 and the marker plate 2 included in the three-dimensional oral cavity region image 35 to further accurately align. I do.

  In a state where the alignment is completed, a part of the three-dimensional oral region image 35 is replaced with the three-dimensional dental model image 25. Thereby, a three-dimensional image as shown in FIG. 6 is obtained.

  In FIG. 6, since the three-dimensional dental model image 25 is directly synthesized with the three-dimensional oral region image 35, the three-dimensional dental model image 25 is trimmed as necessary. A part other than the dentition (mainly the gingival part) is deleted to obtain an image of only the dentition (three-dimensional dentition image) (step S4). Specifically, while looking at the three-dimensional dentition model image 25 displayed on the display means, a predetermined selection area is designated via an input means such as a cursor or a pointer, and the data included in the selection area is three-dimensionally displayed. It erases from the data of the dentition model image 25. The selection area may be input as position data, for example, in coordinates.

  In FIG. 6, the artifact 40 remains, but this is also deleted if necessary (S5). For example, PHANToM (manufactured by SensAble Technologies, USA), which is a haptic device (haptic device), is used to remove the artifact 40. Specifically, while looking at the artifact 40 of the three-dimensional image displayed on the display means, an unnecessary area is designated as a selection area via an input means such as a cursor or a pointer, and data included in the selection area is 3 Delete from the data of the three-dimensional oral region image 35.

  Artifacts may be removed based on the dentition model image after trimming. That is, the artifact extends outwardly from the dentition with the metal restoration, for example as seen in FIG. For this reason, on the basis of the dentition model image after trimming, a region extending outward from the external surface of the dentition model image (dentition) after trimming is input as a selection region, and the three-dimensional oral cavity included in the region is input. By deleting the data of the area image 35, the artifact can be deleted. Further, when the artifact remains partially, the remaining artifact may be removed according to the above-described method.

  With the above steps, a three-dimensional tomographic image of the oral cavity region having the artifact source is completed.

  Here, in the flowchart of FIG. 9, the three-dimensional dental model image 25 is combined with the three-dimensional oral cavity region image 35 (step S3), and then the three-dimensional dental model image 25 is trimmed (step S4) and artifacts are removed (step S4). Although step S5) is performed, after performing trimming (step S4) and artifact removal (step S5) with separate images, both images can be combined (step S3). For example, after displaying two images in an aligned state, trimming (step S4) and artifact removal (step S5) are performed on each image, and finally the two images are combined (step S3). )

FIG. 7 is a three-dimensional image when the method for creating a three-dimensional tomographic image (CT image) according to the present embodiment is applied to a patient performing an implant operation. FIG. 7A is a three-dimensional image before applying this method, and FIG. 7B is a three-dimensional image after applying this method.
As can be seen from FIG. 7, by applying this method, the dentition of the lower jaw, which was unclear due to the artifact, is clearly expressed.

FIG. 8 is a three-dimensional image when the method for creating a three-dimensional tomographic image (CT image) according to the present embodiment is applied to a jaw deformity patient. FIG. 8A is a three-dimensional CT image before application of this method, and FIGS. 8B and 8C are three-dimensional CT images (front and side surfaces) after application of this method.
As can be seen from FIG. 8, by applying this method, the upper and lower dentitions that were obscured by the artifacts are clearly represented on both the front and side surfaces.

  In the present embodiment, the three-dimensional oral region image obtained from the CT image is corrected using the three-dimensional dental model image obtained by CT imaging of the dental model, but the shape of the dental model is You may measure using a contact-type three-dimensional digitizer (brand name ATOS, German GOM company), a laser beam measuring device, and a contact-type measuring device.

  In the present embodiment, an image obtained by CT imaging as a three-dimensional tomographic image has been described. However, the present invention can also be applied to an image obtained by using an MRI (Magnetic Resonance Imaging) method. . When a three-dimensional tomographic image is created using the MRI method, a metal restoration made of Ni—Cr alloy, Co—Cr alloy, Ti, or the like becomes an artifact source.

Next, a computer system for creating a three-dimensional tomographic image according to this embodiment will be briefly described.
FIG. 10 is a schematic diagram of a computer system denoted as a whole by 100. First, the computer system 100 includes an input unit 101 for inputting oral region tomography data / dental model tomography data and the like. Oral region tomography data / dental model tomography data is provided, for example, as DICOM data. Selection regions such as a region to be trimmed and a region to be removed as an artifact are also performed via the input unit.

  The input unit 101 may be a means for selecting a predetermined area of the display means with a pointer or a cursor in addition to a data supply means to a general computer such as supply via the Internet or a CD-ROM.

  The computer system 100 also includes a storage unit 102 that stores oral region tomography data and the like. The storage unit 102 includes a storage medium such as a hard disk or a floppy (registered trademark) disk.

  The computer system 100 also has a control calculation unit 103. The control calculation unit 103 further includes a three-dimensional image creation unit 105 that creates a three-dimensional image from oral region tomography data / dental model tomography data. For example, VGStudio MAX1.1 (manufactured by Volume Graphic) is used to create a three-dimensional image, and DICOM data is converted into three-dimensional data in an STL (Standard Template Library) format.

  The control calculation unit 103 also has a three-dimensional image synthesis unit 106. The three-dimensional image composition unit 106 aligns the three-dimensional oral region image and the three-dimensional dentition model image, and replaces a part of the three-dimensional oral region image with the three-dimensional dentition model image to perform image composition.

  The control calculation unit 103 also includes a trimming unit 107 that trims the three-dimensional dentition model image. For the trimming unit 107, for example, Konica-Minolta Polygon Edition Tool is used.

  The control calculation unit 103 further includes an artifact removal unit 108 that deletes the artifact included in the three-dimensional oral region image. As such a removal unit, for example, PHANToM (made by SensAble Technologies, USA), which is a haptic device, is used.

  The computer system 100 further includes a display unit 104. For the display unit 104, for example, a general display is used.

  Note that the computer system 100 includes other means generally included in the computer system, as necessary.

It is an intraoral photograph of a patient having a metal restoration. 3 is a three-dimensional CT image of a patient having a metal restoration. It is an interface that serves as a reference for alignment. (A) is a dentition model in a state of biting the interface, and (b) is a three-dimensional CT image thereof. (A) is a patient biting the interface, and (b) is a three-dimensional CT image thereof. It is the three-dimensional CT image after the synthesis | combination by this method. It is a three-dimensional CT image of a patient who performs an implant operation, (a) is a three-dimensional CT image before application of this method, and (b) is a three-dimensional CT image after application of this method. It is a three-dimensional CT image of a jaw deformed patient, (a) is a three-dimensional CT image before application of this method, and (b) and (c) are three-dimensional CT images after application of this method. It is a flowchart of a three-dimensional tomographic image creation method. It is the schematic of the computer system for a three-dimensional tomography image.

Explanation of symbols

1 Dental Byte 2 Marker Plate 10 Interface 20 Dental Model 25 Dental Model 3D CT Image 30 Patient 35 Patient 3D CT Image 40 Artifact 100 Computer System

Claims (8)

A method for creating a three-dimensional tomographic image of an oral cavity region having an artifact source using a computer including an input means, a display means, and a computing means,
(A) inputting to the computer via the input means oral region tomography data obtained by tomographic imaging of the oral region of a patient while biting the bite of an interface including a bite and a marker;
(B) a step of inputting tomographic data through the input means tomographic model tomographic data obtained by tomography of a state in which the dental model of the patient bites the bite;
(C) creating a three-dimensional oral region image including the marker from the oral region tomography data and displaying it on the display means;
(D) creating a three-dimensional dentition model image including the marker from the dentition model tomography data, and displaying it on the display means;
(E) The computing means is
The three-dimensional oral region image and the three-dimensional dentition model image are overlaid so that the marker in the three-dimensional oral region image and the marker in the three-dimensional dentition model image substantially match,
Trimming the three-dimensional dentition model image based on the selected region selected via the input means;
Based on the selected region selected via the input means, the artifact included in the three-dimensional oral region image is deleted,
And a step of replacing a part of the three-dimensional oral cavity region image with the three-dimensional dentition model image to form a three-dimensional tomographic image. A method for creating a three-dimensional tomographic image of an oral cavity region having an artifact source using a computer including an input means, a display means, and a computing means,
(A) a step of inputting oral region tomography data obtained by tomographic imaging of a patient's oral region to a computer via an input means;
(B) inputting dentition model data representing the shape of the dentition model of the patient into the computer via the input means;
(C) a step of creating a three-dimensional oral region image from the oral region tomography data and displaying it on a display means; and (d) creating a three-dimensional dental model image from the dental model data, And (e) a calculation means,
Superimposing the three-dimensional oral region image and the three-dimensional dental model image so that the reference point in the three-dimensional oral region image and the reference point in the three-dimensional dental model image substantially coincide with each other,
And a step of replacing a part of the three-dimensional oral cavity region image with the three-dimensional dentition model image to form a three-dimensional tomographic image. The oral region tomography data includes marker position data,
The dentition model data includes marker position data,
The step (e) uses the marker in the three-dimensional oral region image and the marker in the three-dimensional dentition model image as the reference point, and uses the three-dimensional oral region image and the three-dimensional tooth. The method for creating a three-dimensional tomographic image according to claim 2, further comprising a step of superimposing the row model image.   Further, (f) the calculating means includes a step of creating a three-dimensional dentition image by trimming the three-dimensional dentition model image based on the selection region selected via the input means. The three-dimensional tomographic image creation method according to claim 2 or 3.   Further, (g) a step in which the computing means deletes the artifacts included in the three-dimensional oral cavity region image based on the selected region selected via the input means and exposes the three-dimensional dental image. The three-dimensional tomographic image creation method according to claim 4, further comprising: A computer system for creating a three-dimensional tomographic image of an oral cavity region having an artifact source,
Input means for inputting the oral region tomography data of the patient and the dentition model tomography data of the dentition model of the patient;
Display means for displaying a three-dimensional oral region image created from the oral region tomography data and a three-dimensional dental model image created from the dental model tomography data;
A part of the three-dimensional oral region image is placed at a position where the two images are overlapped so that the reference point in the three-dimensional oral region image and the reference point in the three-dimensional dentition model image substantially coincide with each other. Means for replacing the image with a three-dimensional dentition model image,
Trimming means for trimming the three-dimensional dentition model image based on the selected region input via the input means;
A computer system comprising: removal means for removing artifacts included in the three-dimensional oral cavity region image based on the selected region input via the input means.   An interface used for tomography, which is a marker because it is fixed to the bite and the bite, and a tomographic image of the oral region of the patient biting the bite, and the dentition model of the patient biting the bite An interface characterized by superimposing and synthesizing a tomographic image with the marker as a reference point. The interface according to claim 7, wherein the bite is made of a material that is not captured by tomography of the oral cavity region and the dentition model.