WO2009149678A1

WO2009149678A1 - Method and device for generating cephalometric images and recording the joint movement for orthodontic diagnostics using magnet technology

Info

Publication number: WO2009149678A1
Application number: PCT/DE2008/001827
Authority: WO
Inventors: Thorsten Brandt
Original assignee: Orhtotec Oms S.L.
Priority date: 2008-06-09
Filing date: 2008-11-06
Publication date: 2009-12-17
Also published as: DE112008003982A5

Abstract

The application relates to a method and a device for generating cephalometric images of the visceral cranium and recording the joint movement of a patient for orthodontic diagnostics whilst dispensing with X-ray beams. To this end, a mobile head cap is positioned in a non-displaceable fashion on the head of the patient to be examined during the measurement. A magnetic field is generated by coils in the head cap, the latter recognizing 3D data of a measuring pin in the magnetic field. This data is used to register three-dimensional intra-oral and extra-oral points and lines of the human cranium. The software uses these points to calculate an illustrative representation in 2D and 3D, and the evaluation, and a connection with 3D photo scans and with volume tomogram images. The mandible movements can be registered during continuous registration as a result of the obtained mobility of the head.

Description

METHOD AND APPARATUS FOR PRODUCING CEPHALOMETRIC DRAWINGS AND RECORDING THE JOINT MOVEMENT FOR ORTHODONTIC DIAGNOSTICS USING MAGNETIC TECHNOLOGY

Description: Determination of planes, distances and angles within the skull for the joint and face measurement with a head holder with magnetic coils, measuring pin and Meßstifthalter u.a. at the mandibular teeth row.

The new cephalometry presented here without X-ray steels with a mobile head cap represents an alternative to classical cephalostat.

The new cephalometry is based on the three-dimensional registration in the magnetic field. The Carbon Mobile Head Cap, in combination with a 3D Magnetic Scanner, provides a digital imaging and cephalometric evaluation technique for orthodontic diagnostics, treatment planning and assessment of treatment outcomes. One of the problems of conventional cephalometry is accurate and reproducible positioning in the cephalostat and its verifiability the reproducible positioning in the cephalostat is according to Young-Jooh et al [41] an important criterion for the significance of an X-ray image.

Only in the rarely appearing ideal case is the positioning of the projection object perpendicular to the central beam (Ahlquvist et al., 1983 [1, 2, 3], Eliassion et al., 1982 [13]). Numerous studies have dealt with the accuracy of making a lateral cephalograms. It has been found that the manufacturing accuracy of an X-ray image essentially depends on a standardized positioning of the patient. This is particularly important for the follow-up of treatment success in a comparison of the initial image and the intermediate image, as it is not comparable with different positioning [19, 24]. The slightest deviation in an incorrect adjustment of the head already causes the severest degree of asymmetry [41]. 10% of all facsimile sites have such a rotation that they are not evaluable [41]. Küster et al. Significantly changed cephalometric values as early as 4 ° rotation in 1989, and in 10% of all cases, rotations greater than 10 ° were found [21, 41].

In addition, there are other major sources of error, such as the frequent erroneous positioning described by Margolis [24], blurring, blurring, displacement due to movement during shooting, improper development, wrong exposure, unpredictable soft tissue due to a sum of everything [23, 32, 37, 40 ]. All possible efforts have been made to prevent these sources of error [12]. The new mobile head cap eliminates this major source of error This means that movements during registration (recording) have no effect on the digital construction of the cephalogram. Furthermore, the projection is unified and mapped on a scale of 1 to 1 according to nature. This is not possible with previous technology, since different head-foil spacings between 15 and 30 cm and tube distances of 1 m to 4 m with distortions of 3.6% to 17.6%, not only make the comparability difficult, but also distort the recording as such unequal [20, 24, 32, 36]. Efforts to minimize distortion have resulted in greater film X-ray tube spacing, increasing exposure time and radiation dose. With the increased exposure time also increases the risk of blurring, which then ends in blurring of the picture or in a double image. Often, because of the radiation exposure, a second exposure is not required, although the image can not be evaluated. Since these sources of error in the mobile head cap is eliminated, the main advantage of the cephalometry without X-rays in each individual representation of a projection plane in the skull center. Thus, the position of the mobile head cap to the head of the patient is no longer important. One possible source of error when measuring with the mobile head cap is the slipping of the ultralight carbon head cap during the measurement. If a shift of the cap during the measurement is excluded, the respective position on the head has no influence on the measurement result, since the system calibrates itself. The system finds its respective projection plane by entering the anatomical points. Thus, the main advantage lies in the reproducibility of measurements with the mobile head cap.

Another advantage is the measuring process as such, which can stand on a chair.

Normally, the patient is led into the lightless X-ray room and there behind the closed door (so that other people are not contaminated by the scattered radiation, but only the patient is irradiated, are the walls with leaded clothes and the small viewing window made of lead glass). Only by these extreme and necessary precautionary measures the partly irrevocable gene change by x-rays is taken into account (worldwide valid X-ray ordinance: created from the follow-up examination of the Hiroshima victims of 1945. Here it was determined that the leukemia rate remains after more than 50 years of the then surviving victims of the Atomic bomb explosion is still increasing today, It was determined by decree that there is no limitation of exposure to X-rays) Next in the X-ray process in the daily orthodontic practice and in the dental clinics: After entering the X-ray dose in the X-ray book, the patient is led into the X-ray room ,

Here he is clamped in the X-ray machine. Whereby only 4 ° wrong clamping is sufficient to falsify the later evaluation. The fact that the device is rigid, but the Ohrolivenarme have a certain flexibility, and the patient has a certain mass, the correct clamping is difficult, the application of the ear tips and the guidance of the patient via the external auditory canal is very uncomfortable, time-consuming and also later no longer nachkontrollierbar.

Then the patient in the device must stand still and wait for the triggering. This is not pleasant because the X-ray rooms usually have no windows. In addition, resting on the shoulder of the patient of a heavy lead apron, to protect against stray radiation. However, this has the disadvantage that the released by the Compton effect electrons are reflected with higher energy inside the X-ray apron and thus burden the body many times, Röntgen Course 2005 Prof. Becker University Dusseldorf at the LZK Hessen. Therefore, Prof. Becker, Department of Radiology Dusseldorf recommends to omit the apron, since then the burden of reflected scattered radiation is lower. After irradiation, the film is developed or read out by the digital method or viewed directly on the screen. This may cause developmental errors or blurring due to movement of the patient during recording. Nevertheless, these recordings go to the evaluation, since the high radiation exposure, a new shot is usually not made, also lacking the control, since the doctor usually does not carry out the recording and the patient is alone in the X-ray room. With a specific diagnostic software, the image is digitized and then entered the points on the screen. There are some tools to improve the brightness or the contrast to see more details. The resulting data are evaluated in the program for various orthodontic analyzes.

These analyzes, along with all other diagnostic records, provide an overall picture of the patient that enables the orthodontist to make a diagnosis.

The state of the patient described in this way is objective according to the prior art and will also be communicated for research, education and diagnostics. The Values of these measurements may provide a basis for a specific plan for treating a patient. ,.

The preparation of finding the determination of the exact location of the anatomical points and the teeth is so far rather an estimate and this process is far from being an exact science, Prof Ricketts: Bioprogressive Therapy 1968, Publisher Rocky Mountain, San Diego. A complete analysis took up to an hour so far. Orthodontic schools have been teaching this general method of diagnosis and treatment for decades. Meanwhile, many programs perform important tasks in evaluation and planning such as Onyxceph, Evident, FR-Win, Quickceph. While there are several variations of general analysis, most rely on similar types of measurements and points. The main differences are brain points such as the sella in Frankfuter analysis or mandibular angle points such as Xi in the Ricketts analysis, Prof. P. Schopf curriculum of orthodontics, Thieme Verlag 2003. During the orthodontic treatment of a patient, a variety of X-ray images are made. With a view to monitoring the progress of treatment and to the desired goal of the treatment, as well as at the end of the treatment, as well as several years after the completion of the treatment, to find that the treatment was successful.

The problem is solved by the features listed in the claim.

The advantages achieved by the invention are as follows:

1.) The patient is sitting in a normal orthodontic patient chair for examination and is not firmly clamped in an X-ray machine.

2.) The device, ie the ultralight head cap, is placed with 3 pressure points and in 4 minutes the points are picked up with the measuring pin with rounded tip. After the last point the finished analysis will be displayed on the computer monitor. Before that, the examiner is guided through the program in a voice-controlled manner without having to look away from the patient. Only the measuring pin is operated.

3.) By the method of measurement with the head cap placed on the skull, the mobile device with the head for minutes to an immovable unit to create a Mediansagittal, frontal and horizontal plane, which moves virtually with natural movements. So will be the momentary 55 points collected for the generation of cephalometric 3d and 2d values, evaluations and graphical drawings. By the measuring pin of the three-dimensional points is visited on the head of the patient and obtained by the trigger on the measuring pin. The position of the point does not change relative to the head during movements of the patient, since the head cap is fixed by 3 pressure points on the head. Due to the ultralight construction of the coping, the natural movement of patients is not restricted during digitization and as the measuring system moves, the points to the reference system remain constant.

4.) The distortions by the X-ray images of up to 17.6% are omitted, since the magnetic induction measurement system, the 3D coordinates are collected in the ratio 1 to 1.

5.) The comparability of measured values increases with inter-collegial cooperation, since so far different X-ray devices with different long distance lateral X-ray arms have different magnifications of 3.8% to 17.6%.

6.) The accuracy increases because points do not have to be picked out of the superimposed structures of an X-ray image, but the anatomical points partly directly, as can be palpated through the skin in the teeth or bone points.

7.) Asymmetries of the left and right sides can be analyzed separately, since both sides can be measured separately, so far only from the X-ray image could be averaged.

8.) jaw movements can be registered, since the head cap also at

Joint movements firmly fixed with your 3 pressure point on the forehead and the back of the head.

9.) The equipment does not need extra space.

10.) The equipment requires only 220 volts and is mobile, so also on

Schools or in developing countries.

11.) The patient is spared the X-ray dose

12.) The measurement can be repeated as desired. At each repeat measurement, the levels and the space are re-formed and re-measured. If you want to compare the measurement with the X-ray image, each measurement practically corresponds to a new X-ray image with a new evaluation. The invention is characterized by the following features and procedure: Figure 1: drawing of the structure and the device on the patient.

Here you can see the scanner (without the 5V power supply), the source in the head cap with the 3 magnetic coil, the measuring pen and the computer.

Technical specifications:

Scanner and measuring pin equipped with EMC modules.

Update rate

60Hz via sensor, 4kV power supply separated, USB cable optically separated by a light guide Static Accuracy Position / Statistical Accuracy of Positioning 0.22 mm Average / RMS or better Static Accuracy Orientation .5 ° Average RMS or better Latency / Delay when triggered by the Stylus 17ms or better

Relevant values for orthodontics

Resolution position at 30cm ranks / resolution within 30 cm 0.0015in / 0.0038cm or better

Resolution orientation / resolution of orientation in space 0.1 ° or better

Range from Standard Mini Source / Range for the standard configuration in the carbon cap

Up to 5 feet or 1.52 meters / up to 150cm Interface / Connections USB, XPWindows

In the device, that is mobile head cap, 3 integrated magnetic coils, similar to a GPS navigation system, during the measurement with the head forms an immovable unit and determines exactly the position of the measuring pin. Fig. 2: to Fig. 6 show the different projection levels and the fixation of the

Measuring pin on the lower jaw for the jaw movements.

Fig. 2: All 3 projection levels on the patient moving with the patient when the cap is placed on the patient's head. In this room, the values are displayed in 3-dimensional data.

Fig. 3: The median sagittal projection plane on the patient, to which the previous ones from the

Remote x-ray technology known standard analyzes for the side projection can be projected.

Fig. 4: The frontal plane to which the previous from the cephalometric technique known

Standard analyzes for the frontal projection are projected.

Fig. 5: Horizontal plane, the points for horizontal analysis are projected onto this plane.

Fig.6: The measuring pin on the lower jaw to show the lower jaw movements. Here are recorded for the movements of the lower jaw continuous measurements for the jaw movements. The lower jaw moves only to the skull and the head cap, which is immovably positioned on the head.

Fig.7: The superimposition of the acquired 3D data into a 3D photo scan of the patient with fixed matching points, eg: nasion, subnasal and tragus right, from the outside in different projection planes, here for the lateral analysis, but also for the frontal analysis.

Fig. 8: The superimposition of the acquired 3D data into a 3D-photo-scan of the patient from the inside into different projection planes and 3Dimensional, here for the lateral analysis in the middle of the skull - in this case the representation shifted parallel from inside to outside -, but also for the 3D grid representation within the soft tissue shell. The assignment is made by superimposing 1 to 1 points from the photo scan and from the points obtained with the 3D magnetic scanner.

The software program works as follows:

The following subdirectories are created:

1.: patients for patient data and measurements

2 .: sounds for the wave files, so that the 55 points to be measured before the measurements per

Speakers are announced automatically. These wave files can be over the

Windows audio recorder and a microphone also be re-discussed. A backup copy of all data is recommended. Since these files are stored on the computer that is set up for the survey, this data must be from this

Computer to be backed up.

backup

The program DirectCeph sets of each file, z. B. Martin Mustermann, becomes one

Backup copy with the ending Martin Mustermann. old. This is also below

C: orthostar / patients

C: orthotstar / sounds

Transmission of patient files

If the program is installed on another computer, the files must be installed under C: orthostar with subdirectories on the computer under C :.

Then all files and patient data are available again.

Data backup:

They should be separated on a medium, e.g. a USB stick, CD etc. are secured.

Measurement of the points on the patient:

First, the head cap is placed on the patient with about 120 g on the head. With different thickness foam pads, which are replaced by Velcro, the cap can be adapted to different head sizes. The foam rubber set is included. The placement, see photo 1 below, is done with light pressure. The dots are picked up with the gray measuring pen, shown in photo 2. The black dot on the measuring pen is the trigger for registering the points. As a rule, the measuring pen is held like a pencil, with the index finger the foil is pressed down and thereby registers the point.

To clarify the rubber / foil release, the fingerstall used for the measurement has been omitted. The fingerstall can be fixed with a rubber.

How do I know that the cephalometric point has been registered by the computer?

If the trigger fires successfully and a three-dimensional coordinate has been registered, the program will announce the next point, e.g. B: Orbital left.

Using the program.

The program is started by double-clicking on the icon program started via a menu.

Above are the menu items

Patient New Close Survey Images Help (for version display) and information,

Document storage, see Fig. 14.

New patients are recorded via the "Create new" button, where the name and date of birth are entered, as shown in Fig. 9

It is not possible to change this data retrospectively, but it is planned as update 6/08. If incorrect entries have been made here or the name changes, a change must be made in Windows. After the patient is admitted, the button Save is pressed and the measurement menu appears, see Fig. 10.

Then the button "New measurement" is pressed and the scan selection appears on the screen, see Fig. 11.

Here the selection for the measurement for the left face can now be made by the

Press the button "3D Scan left" or the right side of the face through the

Press the button "3D Scan right" to be selected.

For the selection of an X-ray image to be measured directly with the 3D scanner, this must be on a light table or as an expression.

Here the survey can then by the

Press the button "Scan Image with 3D Scanner".

An abort occurs by pressing the "abort" button.

The most used measurement is that of the right side of the face. For this the button "3D scan right" is selected.

If the Sanner or the dongle is not connected correctly, the error message appears on the monitor (Fig. 12).

Otherwise, the survey menu will appear directly. If the start button (Fig. 13) is highlighted in dark. The MEssvorgang begins with the first point. This is announced by the computer speaker and also written on the screen.

This process can take up to 20 seconds, depending on the speed of the computer, as the software protection and the scanner are searched for.

Press the "Start" button with the left mouse button to request the program through the announcement

Scan "Tragus right" to the first point, the percentage of progress of the measurement will be displayed.

For the correct execution of the measurement, the round tip of the stylus is attached to the

Soft tissue point "Tragus right" introduced, under light touch without the

Change soft tissue contour is triggered here with the index finger on the stylus.

After successful triggering, the program immediately says the next one to be measured

Point on.

The points may only be measured by medically trained personnel. For this special courses are to be occupied, in which the measuring and the prospecting, as well as the injury-free finding of the points is practiced.

Then the 55 points are measured and by activating the button on the measuring pin

(Stylus) saved. These 55 points are necessary for the two analyzes mentioned below. For the Brandt 3D analysis, 110 points are necessary because the two

Face halves are measured. Other 3D analyzes are in preparation

At the end "last point" is said and with the mouse on the button "Close and

Save "pressed. Then the pulldown menu appears

When activated by the left mouse button on the possibly existing multiple

Measurements can open as many windows as you like.

By activating the button "Frankfurt / Ricketts" the cephalometric values of the following analyzes are displayed: the Frankfurt analysis (Steiner included), the Ricketts short analysis (11 points)

WITS - Appraisal after Prof. Jacobson.

Standard values and individual deviation according to Schopf and Hasund.

When the following buttons are activated, the corresponding drawings are displayed.

"Ricketts"

When activated, the red teeth drawing will be displayed (Figure 14): in particular, the Wits value can also be seen here.

The integration function converts 3D data from the face scan to the

Scanner points on the right side (Fig. 7) or left side of the magnet system

(noXrayCeph) and the inside (Fig.16). There are both analyzes as 3D

Space lattice. This will be with the 3D X-ray image, at the treatment progress and

Planning is done by overlaying the scanner points, so this

X-rays need not be repeated, but more simulations by

Shifts of 3D magnetic data take place. The same applies to scanned models, which are integrated into the 3D space grid based on the acquired measuring points in the mouth.

The distortions of the X-ray image (Figs. 15, 16, 17, 18) are so severe that the points used are outside the real face dimensions. This is due to the systematic error of a punctiform radiation source (Fig. 19). The X-ray image is particularly inaccurate, because there are different distances from the focus and the object, depending on the model and manufacturer. Because there are no compensation tables, the data sets are not comparable. The method with magnetic technique is a 1 to 1 scale, whereby all data obtained in the future are 1. Anthropological and anatomically correct and 2. always comparable, even with future or other 1 to 1 measurements.

Claims

Claims:

Method and device for generating cephalometric 3D and 2D drawings of the facial skull and recording the joint movement of a patient for orthodontic diagnostics using magnetic technology.

characterized,

that a mobile head cap creates a weak magnetic field by using a measuring pen to register 3-dimensional intra- and extra-oral points and lines of the human skull. From these points, the software computes the mid-sagittal, horizontal, and frontal planes for the 3-dimensional and 2-dimensional graphical representation and evaluation.

Unteranspruch 1 is characterized by:

that by the attachment of the measuring pin to the lower jaw and the movements of the lower jaw can be registered with continuous registration on the 3 levels and 3D in space.

Unteranspruch 2 is characterized by:

that by combining thus obtained points (2D and 3D lattice models) with corresponding 3D coordinates of 3D models of the teeth and 3D scans of the outer skin, as well as of volume tomogram images or MRI images of the same object can be integrated.