METHOD FOR ACQUIRING A DENTAL OBJECT

Abstract

Disclosed herein is a method for acquiring a dental object of a patient with an object volume, in particular at least a part of a skull, an upper jaw and/or a lower jaw. To do so, a plurality of segment volume ranges are defined in the object volume, where the segment volume ranges overlap at most partially and directions of the segment volume ranges are not parallel to one another. The image data of the segment volume ranges is recorded by an MRI machine within a measuring volume of the MRI machine A two-dimensional composite image is generated from the image data of the individual segment volume ranges by projecting the image data onto a target plane. The target plane is disposed parallel to a defined midsagittal 10 plane of the skull or corresponds to the midsagittal plane, where a first segment volume range at least partially includes the midsagittal plane of the skull.

Claims

1. Method for acquiring a dental object of a patient with an object volume, wherein a plurality of segment volume ranges are defined in the object volume, wherein the segment volume ranges overlap at most partially and directions of the segment volume ranges are not parallel to one another, wherein image data of the segment volume ranges is recorded by means of an MRI machine within a measuring volume of the MRI machine, wherein, computer-assisted, a two-dimensional composite image is generated from the image data of the individual segment volume ranges by projecting the image data onto a target plane, wherein the target plane is disposed parallel to a defined midsagittal plane of the object volume or corresponds to the midsagittal plane, wherein a first segment volume range at least partially comprises the midsagittal plane of the skull.

2. Method according to claim 1, wherein a second segment volume range comprises at least a part of an upper jaw and/or a lower jaw, wherein the two-dimensional composite image is generated from the first segment volume range and the second segment volume range by projection onto the target plane.

3. Method according to claim 2, wherein the second segment volume range comprises a left side of the upper jaw and/or the lower jaw, wherein additionally a third segment volume range comprises a right side of the upper jaw and/or the lower jaw, wherein the two-dimensional composite image is generated from the first segment volume range, the second segment volume range and the third segment volume range by projection onto the target plane.

4. Method according to claim 1, wherein with respect to its position and orientation within the measuring volume of the MRI machine, each segment volume range is defined on the basis of a presetting for the respective patient or on the basis of a preliminary image of the object.

5. Method according claim 1, wherein a depth of the segment volume ranges is between

0. 5 mm and 30 mm.

6. Method according to claim 1, wherein the composite image corresponds to a conventional cephalometric radiograph, wherein the target plane of the composite image corresponds to a plane which is disposed parallel to a detector surface of an X-ray detector for a cephalometric radiograph.

7. Method according to claim 1, wherein the image data of the segment volume ranges is recorded by means of the MRI machine, in that a single three-dimensional MRI overall image of the dental object is recorded with the object volume, and the image data of the individual segment volume ranges is carried over from the three-dimensional MRI overall image.

8. Method according to claim 1, wherein the image data of the segment volume ranges is recorded by means of the MRI machine, in that a plurality of MRI segment acquisitions, which display the defined segment volume ranges, are recorded by means of the MRI machine.

8. Method according to claim 8, wherein the individual MRI segment acquisitions are incrementally measured by means of the MRI machine.

10. Method according to claim 8, wherein at least two MRI segment acquisitions are measured at the same time by means of a special MRI machine based on a multislice excitation method.

8. Method according to claim 8, wherein each MRI segment acquisition consists of a single MRI slice image or a stack of multiple MRI slice images, wherein the MRI slice images of a stack are arranged parallel to one another within the respective segment volume range.

12. Method according to claim 1, wherein the midsagittal plane and/or the position and orientation of the individual segment volume ranges of the object volume are defined in that the patient is positioned relative to the MRI machine by a positioning device, or in that a preliminary image of the object volume of the patient is taken and the midsagittal plane is determined manually by a user or automatically by a computer on the basis of the preliminary image.

13. Method according to claim 1, wherein the composite image is generated in a computer-assisted manner from the image data of the individual segment volume ranges by projection of the image data onto the target plane, in that the image data of the individual segment volume ranges is projected onto the target plane in a common projection direction, wherein the projection direction is arranged perpendicular to the target plane.

14. Method according to claim 1, wherein, prior to the acquisition of the individual segment volume ranges in the object volume, the position and/or the orientation of the segment volume ranges in relation to the MRI machine are defined by a user, wherein a head template with an upper jaw template and/or a lower jaw template is schematically displayed by means of a display device, wherein the segment volume ranges and the arrangement thereof in relation to the head template and/or the target plane and/or the midsagittal plane are graphically displayed.

15. Method according claim 1, wherein the generated composite image is displayed by means of a display device, wherein, in addition to the composite image, the image data of at least one segment volume range is displayed by means of the display device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The disclosure is explained with reference to the drawings. The drawings show:

[0065] FIG. 1 a sketch to illustrate the present method,

[0066] FIG. 2 a schematic flow diagram,

[0067] FIG. 3 a sketch with a number of composite images.

DETAILED DESCRIPTION

[0068] FIG. 1 shows a sketch to illustrate the present method for acquiring a dental object 1, in particular at least a part of a skull 2, an upper jaw 3 and/or a lower jaw 4 by means of an MRI machine 5. A first segment volume range is defined, which at least partially comprises a midsagittal plane 7 that is represented by the dash-dotted line. A second segment volume range 8 comprises a left side 9 of the upper jaw 3 and/or the lower jaw 4. A third segment volume range 10 comprises a right side 11 of the upper jaw 3 and/or the lower jaw 4. The segment volume ranges 6, 8 and 10 are cuboid, and have a direction that is defined by the longest edge of the cuboid segment volume range. A first direction 12 of the first segment volume range 6, a second direction 13 of the second segment volume range 8 and a third direction 14 of the third segment volume range 10 are not parallel to one another. The segment volume ranges 6, 8 and 10 overlap only partially. In a first embodiment, the image data of the segment volume ranges 6, 8 and 10 is cut out of an MRI overall image of the entire head 1. In a second embodiment, the image data of the individual segment volume ranges 6, 8 and 10 is generated by performing individual MRI segment acquisitions of the respective segment volume ranges 6, 8 and 10. The image data recorded within a measuring volume 15 of the MRI machine are transmitted from the MRI machine 5 to a computer 16. By means of the computer 16, a two-dimensional composite image 17 is generated from the image data of the individual segment volume ranges 6, 8 and 10 by projecting the image data onto a target plane, wherein the target plane is disposed parallel to the defined midsagittal plane 7. The midsagittal plane 7 of the skull can be defined by positioning the patient relative to the MRI machine 5 with the aid of a positioning device, such as a head holder or a bite holder, or by analyzing a preliminary image of the patient. The generated composite image 17 can be graphically displayed by means of a display device 18, such as a monitor. In addition to the composite image 17, the first image data 19 of the first segment volume 6, the second image data 20 of the second segment volume 8 and the third image data 21 of the third segment volume 10 can be graphically displayed as well. In a schematic representation 22, a head template with a upper jaw template 23 and/or a lower jaw template 24 can be graphically displayed together with the defined segment volume ranges 6, 8 and 10. The arrangement of the target plane 25 relative to the defined segment volume ranges 6, 8 and 10 and a projection direction 26 can likewise be graphically displayed. The schematic representation 22 facilitates the diagnostic analysis of the composite image 17 and the image data 19, 20 and 21 for the user. Input means, such as a keyboard 27 and a mouse 28, are connected to the computer 16 and enable the operation of a virtual tool via a cursor 29, in order, for example, to manually define the position and orientation of the individual segment volume ranges 6, 8 and 10 or the position of the midsagittal plane 7 or the target plane 25. The composite image 17 corresponds to a conventional cephalometric radiograph for conducting a cephalometric diagnostic analysis. Significant anatomical structures, such as a point 30 of the anterior skull base, a point 31 of the bony chin 32, a left mandibular joint axis 33 of the left mandibular joint 34, a right mandibular joint axis 35 of the right mandibular joint 36, are displayed in the composite image 17. In the present composite image 17, the left mandibular joint axis 33 corresponds to the right mandibular joint axis. The distances between said points 30, 31, 33 and 35 can be determined in the cephalometric diagnostic analysis.

[0069] FIG. 2 shows a schematic flow diagram to illustrate an embodiment of the present method. In a first step 40, the segment volume ranges 6, 8 and 10 are defined in relation to the MRI machine. In a first alternative of the second step 41, the image data of the segment volume ranges 6, 8 and 10 is recorded by means of the MRI machine 5, by recording an MRI overall image of the patient's head 1 and cutting the image data of the segment volume ranges 6, 8 and 10 out of the three-dimensional MRI overall image. In a second embodiment of the second step 42, the image data of the segment volume ranges 6, 8 and 10 is recorded by successively measuring individual MRI segment acquisitions by means of the MRI machine 5. In a third step 43, the image data 19, 20 and 21 of the segment ranges 6, 8 and 10 is displayed with the aid of the computer 16 by projection onto the target plane 25, and the composite image 17 is generated.

[0070] FIG. 3 shows a sketch of a variety composite images. As in FIG. 1, the first composite image 50 was generated by projecting the first image data 19 of the first segment volume 6, the second image data 20 of the second segment volume 8 and the third image data 21 of the third segment volume 10 onto the target plane 25.

[0071] In contrast to FIG. 1, the patient exhibits bifacial asymmetry, so that the left mandibular joint axis 33 of the left mandibular joint 34 differs from the right mandibular joint axis 35 of the right mandibular joint 36 in the composite image 50. The teeth 51 of the left side of the jaw 9, which are indicated with solid lines, also differ significantly from the teeth 52 of the right side of the jaw 11, which are indicated with dashed lines.

[0072] The second composite image 53 was generated by projecting the first image data 19 of the first segment volume 6 and the second image data 20 of the second segment volume 8 of the left side of the jaw 9 onto the target plane 25. As a result, only the left mandibular joint 34 and the teeth 51 of the left side of the jaw 9 are displayed.

[0073] The third composite image 54 was generated by projecting the first image data 19 of the first segment volume 6 and the third image data 21 of the third segment volume 10 of the right side of the jaw 11 onto the target plane 25. As a result, only the right mandibular joint 36 and the teeth 52 of the right side of the jaw 11 are displayed.

[0074] The fourth composite image 55 was generated by projecting the first image data 19 of the first segment volume 6 onto the target plane 25. As a result, only the anatomical structures 30, 31 and at least partially the incisors 56 from the first segment volume range 6 can be seen along with the midsagittal plane 7.

[0075] To enable the user to conduct a better diagnostic analysis, the individual composite images 50, 53, 54 and 55 can be displayed simultaneously next to one another, or also one after the other, by means of the display device 18.

REFERENCE SINS

[0076] 1 Head

[0077] 2 Skull

[0078] 3 Upper jaw

[0079] 4 Lower jaw

[0080] 5 MRI machine

[0081] 6 First segment volume range

[0082] 7 Midsagittal plane

[0083] 8 Second segment volume range

[0084] 9 Left side of the jaw

[0085] 10 Third segment volume range

[0086] 11 Right side of the jaw

[0087] 12 First direction

[0088] 13 Second direction

[0089] 14 Third direction

[0090] 15 Measuring volume

[0091] 16 Computer

[0092] 17 Composite image

[0093] 18 Display device

[0094] 19 First image data

[0095] 20 Second image data

[0096] 21 Third image data

[0097] 22 Schematic representation

[0098] 23 Upper jaw template

[0099] 24 Lower jaw template

[0100] 25 Target plane

[0101] 26 Projection direction

[0102] 27 Keyboard

[0103] 28 Mouse

[0104] 29 Cursor

[0105] 30 Point of the anterior skull base

[0106] 31 Point of the bony chin

[0107] 32 Chin

[0108] 33 Left mandibular joint axis

[0109] 34 Left mandibular joint

[0110] 35 Mandibular joint axis

[0111] 36 Right mandibular joint

[0112] 40 First step

[0113] 41 Second step

[0114] 42 Second step

[0115] 43 Third step

[0116] 50 First composite image

[0117] 51 Teeth of the left side of the jaw

[0118] 52 Teeth of the right side of the jaw

[0119] 53 Second composite image

[0120] 54 Third composite image

[0121] 55 Fourth composite image

[0122] 56 Incisors