DE102009060390A1 - Method and system for producing straightened X-ray images for dental or orthodontic diagnostics - Google Patents

Abstract

In a method for preparing straightened X-ray images for dental or orthodontic diagnostics, an X-ray source (28) is inserted in the oral cavity (34) of a patient (36). An X-ray detector (32) is arranged to extend from outside at least a portion of the patient's mandibular arch (36). Then, the teeth of the patient (36) are irradiated with X-radiation, wherein the incident on the X-ray detector (32) X-ray radiation is detected. Based on the X-ray detected by the X-ray detector, a digital X-ray image is generated. According to the invention, the coordinates of a plurality of measuring points located on the teeth (38) are measured by means of a measuring device (50; 64; 73; 50a to 50d; 106a, 106b, 66a, 66b; 110a, 110b; 130). Using these coordinates, the digital X-ray image is finally equalized.

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The invention relates to a method and a system for producing rectified X-ray panorama magnification images for dental or orthodontic diagnostics.

2. Description of the Related Art

For diagnostic purposes, in dentistry and orthodontics, it is often desirable to have panoramic images that show the entire dentition and the entire periodontium of a patient. With such panoramic images, almost exclusively the technology of panoramic tomography (PSA) is used. In this case, the exposure of the image carrier, for example an X-ray film or a storage film, takes place from behind through the skull of the patient. It is ensured by the imaging geometry that only the areas of interest of the skull, namely the teeth with the periodontium apparatus, are sharply imaged. In most cases, the exposure of the image carrier is carried out by a slit diaphragm which moves around the patient's jaw from outside. The X-ray source is simultaneously pivoted around the back of the patient's head. In this way, the respectively illuminated areas of the dentition are projected approximately parallel to the image carrier. The dentition appears on the radiograph as a development of the dentition, which greatly facilitates the diagnosis of a doctor.

A disadvantage of this type of panoramic shots, however, is that the X-rays traverse the entire skull of the patient, and this in places even several times as a result of the scanner-like recording technique. Occasionally, it can not be avoided that even as particularly sensitive to radiation sensitive organs, eg. As the thyroid or the eye lenses that are exposed to X-rays. In addition, the spatial resolution is usually between 2 and 4 line pairs per millimeter and the thickness of the layer shown is low, so that, for example, obliquely grown teeth are often difficult to see.

In addition, it often causes problems that the patient may not move during the relatively long recording time of usually 10 to 15 seconds. For this reason, panoramic tomographic images of the mandibular arch of children, alcoholics or Parkinson's sufferers often fail, which increases the radiation dose in the event of recurrence. Therefore, there were early considerations to introduce an X-ray source into the oral cavity of the patient so as to be able to illuminate the dentition from the inside out with X-rays. The image carrier is arranged so that it extends from the outside around the mandibular arch of the patient around. The advantage of this method is, above all, that a panoramic image of the upper or lower row of teeth or even of the entire dentition can be obtained with a single image. In addition, the X-ray light does not pass through the entire skull of the patient, but only those parts that limit the oral cavity to the front and to the side. For this type of intraoral radiograph, the term panoramic magnification image (PVA) is usually used.

However, according to the PVA principle, operating X-ray devices are no longer in use. The main reason for this is that the x-ray tubes inserted in the mouth had an operating voltage of only about 55 kV, the electron beam current being at 5 mA and copper beam filters being used. Under such operating conditions, a greater portion of the radiation is emitted at relatively long wavelengths, which are very much absorbed by the soft tissue of the oral cavity and therefore result in a high local radiation dose.

Meanwhile, x-ray sources that can be inserted in the mouth have been developed that can be used in the range of 50 to 85 kV with currents of 0.1 mA and smaller. Also, the filters made of copper can be replaced by more suitable materials. In such X-ray tubes, the proportion of long-wave radiation is smaller, which also reduces the radiation dose. The diameter of the focal spot is less than 0.1 mm, and the typical exposure times are between 0.1 and 5 seconds. This allows a resolution of 5 pairs of lines per millimeter, with which caries can be detected by X-ray examination.

However, a problem of the PVA technique remains that the X-ray images are heavily distorted. The reason for this is that the teeth and the periodontal ligaments are not arranged on a spherical shell around the X-ray source. Because of this, many teeth are projected from awkward angles and appear distorted on the X-ray image in a manner that makes diagnosis difficult.

SUMMARY OF THE INVENTION

The object of the present invention is to specify a method and a system with which equalized X-ray images can be generated with an intraorally arranged X-ray source.

• a) Anordnen einer Röntgenquelle in der Mundhöhle eines Patienten;
• b) Anordnen eines Röntgendetektors derart, dass er sich von außen zumindest um einen Teil des Kieferbogens des Patienten herum erstreckt;
• c) Durchleuchten der Zähne des Patienten mit Röntgenstrahlung;
• d) Erfassen der auf den Röntgendetektor auftreffenden Röntgenstrahlung;
• e) Erzeugen eines digitalen Röntgenbildes auf der Grundlage der von dem Röntgendetektor erfassten Röntgenstrahlung;
• f) Messen von Koordinaten von mehreren auf den Zähnen liegenden Messpunkten mit Hilfe einer Messeinrichtung;
• g) Entzerren des digitalen Röntgenbildes unter Verwendung der in Schritt f) gemessenen Koordinaten.

With regard to the method, this object is achieved by a method with the following steps:

• a) placing an X-ray source in the oral cavity of a patient;
• b) arranging an X-ray detector such that it extends from outside at least around a part of the patient's dental arch;
• c) examining the patient's teeth with X-radiation;
• d) detecting the incident on the X-ray detector X-ray radiation;
• e) generating a digital X-ray image on the basis of the X-ray radiation detected by the X-ray detector;
• f) measuring coordinates of a plurality of measuring points located on the teeth by means of a measuring device;
• g) equalizing the digital X-ray image using the coordinates measured in step f).

The invention is based on the finding that, if one knows the position of the X-ray source and the X-ray detector and makes certain typifying assumptions with respect to the position of the teeth to be examined, it is possible to carry out a computational equalization of the X-ray image within certain limits. However, since the position of the teeth relative to the X-ray source and the detector device is only estimated in such typifying assumptions, such an equalization does not allow X-ray images to be obtained, from which, for example, size ratios can be correctly read, as is required for many diagnostic tasks.

Only then, when determining coordinates of a plurality of measuring points lying on the teeth in the manner according to the invention with the aid of a measuring device, the equalization can be carried out so that the proportions of the transilluminated structures are reproduced correctly on the rectified X-ray image.

The X-ray detector used according to the invention can be a digital X-ray detector which contains, for example, a CCD sensor or a CMOS sensor. As an x-ray detector, however, any other image carrier, for example a classical x-ray film or a storage film, is also referred to here. Since the equalization is computer-aided and therefore requires a digital X-ray image, X-ray images generated on classical X-ray films must first undergo digitization.

If a panoramic view of an entire mandibular arch is to be made with the aid of the method according to the invention, then the X-ray detector has to extend from the outside around the entire mandibular arch of the patient. In general, the x-ray detector will be adapted to the approximately parabolic shape of the mandibular arch. However, the X-ray detector may also follow a different course, for. B. the path of a circle or an ellipse. Especially if the X-ray detector has an exchangeable image carrier, for. As a storage film or an X-ray film, it may be advantageous if the X-ray detector is composed of a plurality of plate-shaped elements which enclose an angle at their joints. Also, a subdivision of the X-ray detector into individual curved segments for the upper or lower mandibular arch and / or the right or left half of the dentition can be useful in many cases. Particularly advantageous is an arrangement in which a segment is provided for each row of teeth and the two segments in an vertical plane an angle, z. B. of about 160 ° include. The only requirement is that the position and shape of the X-ray detector is known with sufficient accuracy, because this information is needed for the equalization in step g).

The same applies to the case that not the entire mandibular arch in the manner of a panoramic view, but only a part of the dentition or even a single tooth should be recorded on the X-ray image.

The measuring points whose coordinates are measured by means of the measuring device can be distributed in different ways on the teeth. The distribution of the measuring points can be regular or irregular, loose or dense. The measurement points may also be limited to parts of the denture, which experience has shown that the distortion is particularly large or in which a measurement is easier to perform. Furthermore, the measuring points can be arranged linearly and in particular form a line grid. It may even be sufficient to measure the coordinates of only a few measuring points on a few teeth, eg. B. from measuring points on the cutting edges of the incisors.

If the coordinates of the measuring points are measured with a measuring device, this itself represents a reference system for the coordinates. If the position of the measuring device relative to the X-ray detector and the X-ray source is known, the equalization can be carried out relatively easily. As a reference point relative to which the coordinates of the teeth can be determined in step f), for example, a bite point of the patient can be determined. By this one understands a certain, mostly on the incisors point, relative to which both the X-ray source and the X-ray detector and the measuring device can be aligned. For this purpose, it is generally sufficient to attach a bite bar to the corresponding components, which is provided with a notch into which the respective incisors can engage in a defined position.

If the coordinates of the teeth relative to the X-ray detector and the X-ray source are known, then in step g) it is possible to determine from the measured coordinates of the teeth an object surface arranged between the X-ray source and the X-ray detector, in which the teeth are arranged. The rectified X-ray image is then determined by back-projection of the X-ray image onto the object surface. This procedure is particularly simple and leads to an equalized X-ray image, which appears similar to a processed under parallel projection processing. It is exploited that the X-rays pass through the teeth in the PVA technique due to the arrangement of the X-ray source in the oral cavity and the inclination of the teeth rather vertical than is the case with the PSA technique.

Since it is not always easy to perform a measurement of the teeth according to step f) from the oral cavity and thereby to maintain a precisely defined position relative to the x-ray source and the x-ray detector, methods can also be used in which such an absolute reference is not required , These methods also make it possible to freely set the desired perspective within certain limits.

• ga) Festlegen einer Sollperspektive für das entzerrte Röntgenbild;
• gb) Entzerren des Röntgenbildes derart, dass das Röntgenbild aus der in Schritt ga) festgelegten Sollperspektive aufgenommen erscheint.

In such a method, in which the coordinates of the teeth (only) relative to each other must be determined, the step g) comprises the following steps:

• ga) determining a desired perspective for the rectified X-ray image;
• gb) equalizing the X-ray image in such a way that the X-ray image appears from the desired perspective determined in step ga).

• gba) Erzeugen eines Kantenbildes des Röntgenbildes unter Verwendung eines Kantendetektions-Algorithmus;
• gbb) Ableiten eines dreidimensionalen Oberflächenreliefs der Zähne aus den an den Messpunkten gewonnenen Koordinaten;
• gbc) Darstellung des Oberflächenreliefs aus der in Schritt ga) festgelegten Sollperspektive;
• gbd) Auswahl von Stützpunkten auf dem in Schritt gbc) dargestellten Oberflächenrelief und Zuordnen der Stützpunkte zu entsprechenden Punkten auf dem in Schritt gba) erzeugten Kantenbild;
• gbe) Ableiten einer Transformationsvorschrift, welche die entsprechenden Punkte auf dem Kantenbild in die in Schritt gbd) ausgewählten Stützpunkte umrechnet;
• gbf) Anwenden der Transformationsvorschrift auf das in Schritt e) aufgenommene digitale Röntgenbild.

In image processing, various algorithms are known with which optically recorded images can be compared with three-dimensional surface reliefs. Particularly suitable for the equalization desired here is a method in which step gb) comprises the following steps:

• gba) generating an edge image of the X-ray image using an edge detection algorithm;
• gbb) deriving a three-dimensional surface relief of the teeth from the coordinates obtained at the measurement points;
• gbc) representation of the surface relief from the desired perspective determined in step ga);
• gbd) selection of vertices on the surface relief depicted in step gbc) and assignment of the vertices to corresponding points on the edge image generated in step gba);
• gbe) deriving a transformation rule which converts the corresponding points on the edge image into the vertices selected in step (bbd);
• gbf) applying the transformation rule to the digital x-ray image taken in step e).

The desired perspective, in which the three-dimensional surface relief of the teeth derived from the measuring points is represented in step gbc), can be set unchangeably by the programming, but also freely selectable within certain limits by an operator. In addition, different target perspectives can be defined for individual parts of the surface relief, so that, for example, each individual tooth is represented centrally in perspective. In addition, the vanishing point can be freely selected, for example at the height of the tooth crown or the tooth root. The desired perspective can also be individual parallel perspective for each tooth, resulting in a developed representation as in conventional panoramic images. Depending on the problem posed in diagnostics, one or the other perspective may be more favorable, so that a choice opens up improved diagnostic options.

Since the geometric conditions in the examination of the dentition with an intraorally arranged X-ray source change from tooth to tooth, it may be useful if the transformation rule contains several sub-regulations that convert parts of the X-ray image. Thus, possibly more distorted molars may require a different transformation than cutting teeth, which are penetrated approximately perpendicularly by the X-ray radiation. In particular, exactly one tooth or a certain number of teeth can be represented on each subarea of the x-ray image which is equalized with the aid of a separate partial prescription.

The embodiment explained above, in which transformation instructions are derived using support points, requires an assignment of the support points to corresponding points on the edge image generated in step gba). In principle, this assignment can be carried out manually for one or more interpolation points, especially if ambiguities can not be ruled out. Preferably, however, this assignment is carried out automatically, wherein an edge image of the surface relief is generated from the surface relief represented in step gbc) by means of edge detection and corners or other characteristic support points are automatically predefinable Selection criteria are selected based on the edge image.

As a measuring device for measuring the coordinates of the measuring points lying on the teeth can be made of a variety of distance sensors, which are known per se in the prior art. Triangulation sensors or ultrasound sensors with one or more ultrasound sources (so-called phased array ultrasound sensors) are also well suited for intraoral measurement.

Alternatively, in step f) a plurality of overlapping camera images can be taken from different intraoral positions and the coordinates of the measuring points can be derived therefrom. This can be done, for example, using a 3D camera having two mutually offset image pickup. However, the different camera images can also be recorded by one and the same camera if they are taken from different places at different times. Also with a camera and a light pattern projected on the teeth, z. As a light grid, coordinates of measuring points can be determined. The use of cameras additionally has the advantage that additional intraoral images are available for the diagnosis, which can provide additional information on the status of the teeth.

The cameras can be designed as endoscopes which transmit the image information optically via a fiber bundle to an image sensor. Also so-called video endoscopes, in which the image sensor is located in the recording head and the data transmission takes place electrically, of course come into consideration.

To determine the coordinates of the measuring points in step f), a light pattern, for. As a dot or stripe pattern, generated on the teeth and detected by directional optical sensors. In contrast to the use of a triangulation sensor whose light beam passes over the teeth like a scanner, in this way the coordinates of the measuring points lying on the light pattern can be detected in a single measurement process.

In one embodiment of the invention, a calibration step is provided in which an X-ray image without patients is initially recorded. Then, pixel-wise or uniformly for areas of pixels is determined by which correction amounts the intensity must be changed to obtain a constant intensity across the X-ray image. Later generated X-ray images of teeth are then corrected for their intensity taking into account the correction amounts. In this way, it is ensured that any parts of the measuring device which may be present in the beam path of the X-radiation and which absorb the X-ray light (even if only slightly) are not recognizable on the later X-ray images. Such a calibration step further prevents other influences from leading to undesired brightness differences in the X-ray images. These influences include, for example, the generally non-spherical shell shape of the X-ray detector, which lead to different distances between locations on the X-ray detector and the X-ray source, but also a spatially inhomogeneous radiation of the X-ray source and local fluctuations in the sensitivity of the X-ray detector.

• a) Anordnen einer Röntgenquelle in der Mundhöhle eines Patienten;
• b) Anordnen eines Röntgendetektors derart, dass er sich von außen zumindest um einen Teil des Kieferbogens des Patienten herum erstreckt;
• c) Durchleuchten der Zähne des Patienten mit Röntgenstrahlung;
• d) Erfassen der auf den Röntgendetektor auftreffenden Röntgenstrahlung;
• e) Erzeugen eines digitalen Röntgenbildes auf der Grundlage der von dem Röntgendetektor erfassten Röntgenstrahlung;
• f) Aufnehmen eines Röntgenbildes ohne Patienten;
• g) bildpunkt- oder bereichsweise Ermitteln, um welche Korrekturbeträge die Intensität verändert werden muss, um eine über das Röntgenbild hinweg konstante Intensität zu erhalten;
• h) Korrektur später von Zähnen des Patienten erzeugter Röntgenbilder bezüglich ihrer Intensität unter Berücksichtigung der Korrekturbeträge.

Such a calibration step can advantageously also be carried out independently of steps f) and g). The Applicant therefore reserves the right to claim protection in a divisional application for a method for producing X-ray images for dental or orthodontic diagnostics, comprising the following steps:

• a) placing an X-ray source in the oral cavity of a patient;
• b) arranging an X-ray detector such that it extends from outside at least around a part of the patient's dental arch;
• c) examining the patient's teeth with X-radiation;
• d) detecting the incident on the X-ray detector X-ray radiation;
• e) generating a digital X-ray image on the basis of the X-ray radiation detected by the X-ray detector;
• f) taking an X-ray image without patients;
• g) determining pixel-wise or area-wise by which correction amounts the intensity must be changed in order to obtain a constant intensity across the X-ray image;
• h) correction of X-ray images later generated by teeth of the patient with regard to their intensity taking into account the correction amounts.

If the x-ray detector has an exchangeable image carrier, in particular a storage film or an x-ray film, then a marking object can be arranged in the beam path of the x-ray radiation which is imaged on the image carrier. The position of the image carrier relative to the X-ray source can then be determined from the position of the image of the marking object on the image carrier. This measure is particularly advantageous if there is a risk that the interchangeable image carrier is not exactly aligned in a recording provided for him. Such an exact alignment is often not already ensured because the image carrier with sufficient play must be inserted into the recording, so that no exact target position of the image carrier is guaranteed. The marking object according to the invention, the position of which is fixed relative to the X-ray source, then makes it possible to detect such deviations of the actual position of the image carrier from its nominal position and, if appropriate, to correct the remaining image accordingly.

• a) Anordnen einer Röntgenquelle in der Mundhöhle eines Patienten;
• b) Anordnen eines Röntgendetektors derart, dass er sich von außen zumindest um einen Teil des Kieferbogens des Patienten herum erstreckt, wobei der Röntgendetektor einen auswechselbarer Bildträger, insbesondere eine Speicherfolie oder einen Röntgenfilm, aufweist;
• c) Anordnen eines Markierungsobjekts im Strahlengang der Röntgenstrahlung, das auf den Bildträger abgebildet wird;
• d) Durchleuchten der Zähne des Patienten mit Röntgenstrahlung;
• e) Erfassen der auf den Röntgendetektor auftreffenden Röntgenstrahlung;
• f) Erzeugen eines digitalen Röntgenbildes auf der Grundlage der von dem Röntgendetektor erfassten Röntgenstrahlung;
• g) Ermitteln der Position des Bildträgers relativ zu der Röntgenquelle aus der Lage des Bildes des Markierungsobjekts auf dem Bildträger;
• h) Entzerren des digitalen Röntgenbildes unter Verwendung der in Schritt g) ermittelten Position.

Such a marking object can advantageously also be introduced into the beam path of the X-radiation independently of a measurement of the teeth according to steps f) and g). The Applicant therefore reserves the right to claim protection in this application or a divisional application for a method for producing X-ray images for dental or orthodontic diagnostics, comprising the following steps:

• a) placing an X-ray source in the oral cavity of a patient;
• b) arranging an X-ray detector such that it extends from the outside at least around a part of the patient's dental arch, the X-ray detector having an exchangeable image carrier, in particular a storage film or an X-ray film;
• c) arranging a marking object in the beam path of the X-ray radiation which is imaged on the image carrier;
• d) X-raying the patient's teeth;
• e) detecting the incident on the X-ray detector X-ray radiation;
• f) generating a digital X-ray image on the basis of the X-ray radiation detected by the X-ray detector;
• g) determining the position of the image carrier relative to the x-ray source from the position of the image of the marking object on the image carrier;
• h) equalizing the digital X-ray image using the position determined in step g).

If the X-ray detector has an exchangeable image carrier, in particular a storage film or an X-ray film, then this image carrier can carry a plurality of markings, which are transmitted to the digital X-ray image when the image carrier is read out. It can then be seen from the location of the markings on the digital X-ray images inhomogeneities of the image carrier and correct mathematically in the equalization.

• a) Anordnen einer Röntgenquelle in der Mundhöhle eines Patienten;
• b) Anordnen eines Röntgendetektors derart, dass er sich von außen zumindest um einen Teil des Kieferbogens des Patienten herum erstreckt, wobei der Röntgendetektor einen auswechselbarer Bildträger, insbesondere eine Speicherfolie oder einen Röntgenfilm, aufweist, der mehrere Markierungen trägt, die beim Auslesen des Bildträgers auf das digitale Röntgenbild übertragen werden;
• c) Durchleuchten der Zähne des Patienten mit Röntgenstrahlung;
• d) Erfassen der auf den Röntgendetektor auftreffenden Röntgenstrahlung;
• e) Erzeugen eines digitalen Röntgenbildes auf der Grundlage der von dem Röntgendetektor erfassten Röntgenstrahlung;
• f) Entzerren des digitalen Röntgenbildes, wobei aus der Lage der Markierungen auf dem digitalen Röntgenbild Inhomogenitäten des Bildträgers erkannt und rechnerisch korrigiert werden.

Also, this measure is applicable regardless of a measurement of the teeth in steps f) and g), so that the applicant reserves the right to seek protection for a method for producing X-ray images for dental or orthodontic diagnostics in a divisional application, the following Steps includes:

• a) placing an X-ray source in the oral cavity of a patient;
• b) arranging an X-ray detector such that it extends from the outside at least around a part of the patient's dental arch, the X-ray detector having an exchangeable image carrier, in particular a storage film or an X-ray film, which carries a plurality of markings which are present when the image carrier is read the digital X-ray image is transmitted;
• c) examining the patient's teeth with X-radiation;
• d) detecting the incident on the X-ray detector X-ray radiation;
• e) generating a digital X-ray image on the basis of the X-ray radiation detected by the X-ray detector;
• f) equalizing the digital X-ray image, wherein inhomogeneities of the image carrier are detected and mathematically corrected from the position of the markings on the digital X-ray image.

• a) eine in einer Mundhöhle eines Patienten anordenbare Röntgenquelle;
• b) einen Röntgendetektor, der derart anordenbar ist, dass er sich von außen zumindest um einen Teil des Kieferbogens des Patienten herum erstreckt, und mit dem auf den Röntgendetektor auftreffende Röntgenstrahlung erfassbar ist;
• c) einen digitalen Speicher zum Speichern eines Röntgenbildes, das von dem Röntgendetektor nach Durchleuchten von Zähnen des Patienten aufgenommen worden ist;
• d) eine Messeinrichtung zum Messen von Koordinaten von mehreren auf den Zähnen liegenden Messpunkten;
• e) eine Entzerrungseinrichtung, die zum rechnergestützten Entzerren des Röntgenbildes unter Verwendung der in Schritt f) gemessenen Koordinaten eingerichtet ist.

The object mentioned in the introduction is achieved with regard to the system by a system which comprises:

• a) an X-ray source which can be arranged in an oral cavity of a patient;
• b) an X-ray detector which can be arranged such that it extends from the outside at least around a part of the patient's dental arch, and with which X-radiation impinging on the X-ray detector can be detected;
• c) a digital memory for storing an X-ray image taken by the X-ray detector after examining teeth of the patient;
• d) a measuring device for measuring coordinates of a plurality of measuring points located on the teeth;
• e) an equalization device, which is set up for the computer-aided equalization of the X-ray image using the coordinates measured in step f).

The measuring device may comprise an optical triangulation sensor and / or an ultrasound sensor and / or a 3D camera.

In one embodiment, the measuring device comprises a light source, with which a light pattern can be projected onto the inner or outer surface of the teeth, and an (possibly direction-resolving) optical sensor for detecting the light pattern. With such a measuring device, the coordinates of the measuring points on the teeth can be measured without contact and with high accuracy.

In some embodiments, the measuring device is configured for an intraoral arrangement. This has the advantage that even the molars can be surveyed well, which appear particularly distorted in panoramic magnification shots. As far as "set up" is mentioned here, this means that the measuring device will often not be permanently located at the relevant location (in the oral cavity of the patient), but only during the measuring process. At other times, the relevant parts of the measuring device may be disassembled, swung away or otherwise removed.

In contrast, in other embodiments, the measuring device is set up for an extraoral arrangement. This has the advantage that not in addition to the X-ray source other devices must be introduced into the oral cavity of the patient, which can cause a malaise or even a choking reflex in this. Considered, for example, to use a mechanical roller switch, which can be firmly connected to the X-ray machine and before or after the fluoroscopy, the series of teeth of the patient descends and detects the coordinates of the worn teeth.

With an extra-oral arrangement of the measuring device, different variants can be distinguished. If the measurement of the teeth does not take place simultaneously with the fluoroscopy of the teeth, but before or after, the measuring device can be arranged during the measuring procedure so that X-ray-impermeable parts are arranged at locations which pass through such X-rays during fluoroscopy, which also penetrate teeth and other structures of interest. In this case, it is necessary that these parts of the measuring device can be swung out of the beam path of the X-radiation or removed in any other way. In this context, parts which absorb more than 50% of the incident X-radiation are considered to be impermeable to X-rays.

Ideally, however, the measurement of the teeth takes place simultaneously with their fluoroscopy. In this way, it is ensured that the patient does not move between the measurement of the teeth and their fluoroscopy and thus possibly distorts the equalization of the X-ray images. In this case, however, it must be ensured that the measuring device does not affect the X-ray image.

This can be done, for example, by arranging the measuring device for an arrangement in which parts of the measuring device which are impermeable to X-radiation are not penetrated by X-rays which have previously been through-toothed. In this way it is ensured that the images of these parts on the X-ray image do not cover the teeth or other structures of interest.

As a location for an arrangement of these parts is, for example, the area above the upper mandibular arch and under the lower mandibular arch into consideration. However, from there, the teeth can only be poorly achieved for a measurement. Therefore, parts of the measuring device which are impermeable to X-radiation can preferably be arranged in a plane which, with the patient's mouth open, extends between its upper and lower rows of teeth. Since the patient must have opened the mouth anyway because of the introduction of the X-ray source, remains between the rows of teeth, a relatively large gap, which is available for an array of radiopaque parts of the measuring device.

The measuring device can generally be arranged at least partially for an arrangement between the patient and the X-ray detector. Such an arrangement has the advantage that the X-ray detector does not interfere with the measurement of the teeth. Such a measuring device can, for. B. comprise a contour measuring arc, which extends in a measuring plane and has contact surfaces for engagement with a row of teeth. The shape of the contour measuring arc is adjustable in the measuring plane in order to bring the contact surfaces into contact with the row of teeth. The measuring device further comprises means for determining the shape of the contour measuring arc. The contour measuring arc is preferably permeable to X-ray radiation, so that the contour measuring arc can remain in place during transillumination.

Such a contour measuring arc is also advantageous insofar as it can be pushed under appropriate design under the lips of the patient, so that even some molars can be measured, which are otherwise not or at least not readily accessible for a extraorally arranged measuring device.

The means for determining the shape of the contour measuring arc may be sensors that are integrated into the contour measuring arc. If, for example, the contour measuring arc has a plurality of contact members which are connected to one another by joints, then the sensors integrated in the contour measuring arc can be provided to determine the deflections of the joints. The shape of the contour measuring arc can then be derived from the deflections of the joints.

However, the means for determining the shape of the contour measuring arc can also with the Contour contour arc associated absorption bodies that are impermeable to X-rays. The absorption bodies are arranged in such a way that X-ray radiation, which is absorbed by the absorption bodies, has not previously illuminated through teeth. The position of the absorption body can then be determined by the equalization device, which allows an immediate inference to the shape of the contour measurement arc. In such an embodiment, the expense of a sensor that is integrated into the contour measuring arc is eliminated.

Especially when a sensor integrated into the contour measuring arc is not required, the contour measuring arc can comprise a plastically deformable carrier. This is then simply applied to the patient's row of teeth for the purpose of measuring and deformed in such a way that the largest possible contact is achieved over the entire length of the contour measuring arc.

In other embodiments, the measuring device is at least partially set up for an arrangement on a rear side facing away from the patient of the X-ray detector. Such an arrangement has the advantage that comparatively much space is available for the arrangement of the measuring device. The X-ray detector should, however, if possible only have a detection surface there where teeth and other structures of interest can be imaged. In the already mentioned space between the two rows of teeth of the patient, an X-ray detector is not needed, so that there may be arranged advantageously the measuring device.

In particular, the X-ray detector may have an opening which is arranged in such a way that X-ray radiation which has passed through the opening has not previously illuminated through teeth. The measuring device is then arranged in such a way behind the X-ray detector in the region of the opening, that the opening allows a visual connection between the measuring device and the teeth.

It is also possible to arrange some parts of the measuring device in the area between the X-ray detector and the patient and other parts outside this area. For example, the measuring device can have a reflector which is set up for an arrangement between the patient and the X-ray detector and is reflective for light or sound waves and transparent for X-ray radiation. Since the reflector can be arranged in an optimal position relative to the measuring teeth, so that the teeth can optically or by means of ultrasonic waves u. U. even better measured, as if the corresponding sensors of the measuring device between the rows of teeth of the patient are arranged.

In another group of embodiments, the measuring device comprises a spatially resolving upbeat sensor by means of which the coordinates of a contact surface of a tooth and / or the lip of the patient can be measured at least along one direction. The contact surface of a tooth will most often be the cutting edge of the incisors; in principle, however, a detection of the adjacent canines is also considered if the Aufbisssensor has a sufficient width. Although only a few teeth can be measured with such a spatially resolving Aufbisssensor and also for this only measuring points that lie on the contact surface, but at least the important information is obtained as far as the incisors of the X-ray source is removed. The position of the remaining teeth must then be extrapolated. In general, at least the sex and the age of the patient will be taken into account in order to be able to assume a typical form of the mandibular arch. This typical shape can z. B. obtained by averaging measurements that were obtained in the measurement of the mandibular arches of a variety of comparable patients.

In one embodiment, the bite sensor has a bite element that is displaceable along an adjustment direction and provided with a bite notch. Furthermore, the bite sensor comprises a position sensor with which the position of the bite element along the adjustment direction can be measured. The provision of a bite-on notch in the bite sensor reduces the risk of the patient unintentionally leaving a position relative to the x-ray source due to minor jaw movements, which has previously been adjusted and provides the basis for the subsequent equalization of the x-ray image.

The bite sensor may include a motor for displacing the bite element. In this way, a desired distance between the incisors of the patient and the X-ray source can be input via an input device. The X-ray system then automatically sets the desired distance with the help of the motor. If the bite element has exactly one bite notch on each side, there is no danger of the patient accidentally placing their incisors in the wrong bite-off notch or switching them shortly before candling through smaller jaw movements.

If the motor is designed as a servomotor, this can also serve as a position sensor.

The bite element may have a sleeve-shaped base body, which on an insertion part of the X-ray device, which is the X-ray source contains, is slidably disposed along a longitudinal axis of the insertion. The insertion part thus serves at the same time as a guide for the bite element, which simplifies the construction of the Aufbisssensors. Alternatively, however, it is also possible to provide on a sleeve-shaped base body at the top and bottom of each receiving slot, in which a strip-shaped bite element is arranged linearly movable.

The on-bead sensor may comprise at least one sensor element and a carrier carrying the at least one sensor element and being partially insertable into the oral cavity of the patient. At least the coordinates of the contact surface along a reference direction can be determined by the at least one sensor element. In this case, the incisors of the patient do not engage in a bite notch but abut at any location with their cutting edge on the bite sensor. This location is detected by the at least one sensor element. Such an embodiment is particularly advantageous if the measurement of the coordinates of the incisors is performed simultaneously with the fluoroscopy. In this case, there is no danger that the patient accidentally changes a previously set position of the incisors on the up to the moment of the X-ray.

The at least one sensor element may comprise a plurality of pressure or proximity sensors successively arranged along the reference direction, the size and arrangement of which determines the spatial resolution with which the coordinates of the contact surface can be measured. For example, piezo elements are particularly suitable as pressure sensors. As proximity sensors in particular capacitive sensors come into consideration, which can be specifically designed so that they respond only to teeth, only on lips or on the lips and teeth.

In another embodiment, the at least one sensor element is designed as a linear potentiometer, which has a resistance surface and an elastic electrode. A movable tapping point of the linear potentiometer can be generated where the elastic electrode is deflected by a tooth and / or the lip of the patient so far that the electrode rests against the resistance surface. Such a linear potentiometer has a simple structure and requires fewer electrical leads than a plurality of successively arranged pressure or proximity sensors.

The carrier for the at least one sensor element is preferably fastened on an insertion part, which contains the X-ray source, and may for example be designed as a sleeve, which is pushed onto the insertion part.

For further advantages and developments with respect to the system, reference is made to the above explanations of the method.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparent from the following description of an embodiment with reference to the drawings. Show:

1 a vertical section through an inventive X-ray examination system in use;

2 a horizontal section through the in the 1 X-ray examination system shown;

3 a schematic representation for illustrating a resulting on an X-ray image distortion;

4 a schematic representation similar to that in the 3 but with an undistorted image;

5 a schematic representation similar to that in the 3 but with another projected body;

6 a schematic representation similar to that in the 3 , but with emphasis on an object plane;

7 to explain a first embodiment of a method according to the invention an enlarged view of the geometric relationships that in the projection of teeth on the sensor surface of an X-ray detector of the in the 1 and 2 present X-ray examination system are present;

8th a vertical section through a triangulation sensor used as a measuring device, which is inserted into the oral cavity of a patient;

9 a front view of the in the 8th shown triangulation sensor;

10 a vertical section through a stereoscopic 3D camera, which is inserted into the oral cavity of a patient;

11 a front view of the in the 10 shown 3D camera;

12 a regular light grid generated by a light source;

13 the light grid according to 12 when projecting on teeth;

14 a suitable for carrying out the method according to the invention measuring device having a plurality of light sources and a plurality of detectors for carrying out a triangulation;

15 a schematic representation of essential steps of the inventive method according to a second embodiment, in which the X-ray image can be equalized so that it appears taken from a desired target perspective;

16 a flowchart in which essential steps of the method according to the invention are shown;

17 a vertical section through an inventive X-ray examination system according to an embodiment in which a measuring device is attached to a distal end of an insertion part;

18 a horizontal section through an inventive X-ray device according to an embodiment in which the measuring device between the patient and the X-ray detector is arranged;

19 a front view of the in the 18 shown measuring device at the height of the line XIX-XIX, wherein the X-ray detector and a holder connected thereto are not shown;

20 a horizontal section through an inventive X-ray device, in which a measuring device is arranged on a side facing away from the patient side of the X-ray detector;

21 a front view of the in the 20 shown measuring device at the height of the line XXI-XXI, wherein the X-ray detector and a holder connected thereto are not shown;

22 a vertical section through an inventive X-ray device according to an embodiment in which reflectors are arranged between the patient and the X-ray detector;

23 a horizontal section through an inventive X-ray device according to an embodiment in which the measuring device comprises a hinged contour measuring arc with integrated sensors;

24 a front view of the in the 23 shown measuring device at the height of the line XXIX-XXIX, wherein the X-ray detector and a holder connected thereto are not shown;

25 a horizontal section through an inventive X-ray device according to an embodiment in which the measuring device comprises a plastically deformable contour measuring arc with it carried absorption bodies;

26 a front view of the in the 25 shown measuring device at the height of the line XXVI-XXVI, wherein the X-ray detector and a holder connected thereto are not shown;

27 a vertical section through an inventive X-ray device according to an embodiment, wherein the measuring device comprises a Aufbisssensor with a plurality of successively arranged pressure sensors;

28 an enlarged section of the 27 in which the arrangement of the pressure sensors designed as piezoelectric elements can be recognized;

29 one to the 28 ajar partial sectional view of a Aufbsssssors according to an embodiment in which the sensors are capacitive proximity sensors;

30 one to the 28 angled fragmentary sectional view of a Aufbsssssors according to an embodiment, in which the Aufbsssensor comprises a linear potentiometer;

31 a vertical section through an inventive X-ray device according to an embodiment in which the Aufbisssensor has a motor-displaceable sleeve.

DESCRIPTION OF PREFERRED EMBODIMENTS

1. Basic structure of the X-ray examination system

The 1 and 2 show an inventive and overall with 10 designated X-ray examination system for dental and orthodontic diagnostics in a vertical or horizontal section.

The X-ray examination system 10 has an x-ray machine 12 on, that over a data line 14 with a computer 16 connected is. Instead of the computer 16 may also be a special for the x-ray examination system 10 developed evaluation unit may be provided which has a data memory and a computing unit.

The X-ray machine 12 has a protective housing 18 on, that of an electric and thermal insulating material and in a cuboid main part 20 and a tubular insertion part 22 is divided. The insertion part 22 is at the main part 20 releasably secured by a fastening device, not shown, and takes an X-ray tube, the sake of clarity in the 1 and 2 not shown in detail.

In the main part 20 of the protective housing 18 is an electron beam source 24 arranged, with which an electron beam can be generated. The electron beam source 24 has for this purpose in a conventional manner, a cathode and an anode, which are connected to a high voltage source, which is also in the main part 20 of the protective housing 18 is recorded. During operation of the X-ray machine 12 For example, electrons are emitted from the cathode and accelerated in the electric field that forms between the cathode and the anode. The electrons leave the electron beam source through a hole provided in the anode 24 and form an electron beam in the x-ray tube 26 , This hits a target at the rear end of the x-ray tube 27 that in the illustrated embodiment has the shape of a truncated cone. When hitting the target 27 The electrons are slowed down and release X-rays, which are in the 1 and 2 with dashed lines 30 is indicated. The tip of the target 27 on which the electron beam 26 impinges, thus provides one below 28 designated point-shaped X-ray source.

The X-ray machine 12 also has an X-ray detector 32 on, which is formed in the illustrated embodiment as a digital X-ray detector and with the aid of a holder 31 at the main part 20 of the protective housing 18 is attached. The x-ray detector 32 has for this purpose a CCD or a CMOS sensor whose pixels are on a sensor surface 33 are arranged, both in the sectional plane according to the 1 as well as the cutting plane according to the 2 is curved. The curvature in the horizontal sectional plane according to the 2 is chosen so that it follows roughly the typical course of a human mandibular arch. Describe the detector surface of the X-ray detector 32 by moving a circular arc along an approximately parabolic path. Behind the x-ray detector 32 can still be arranged a shield (not shown), which prevents that not absorbed by the X-ray detector X-ray propagates in the examination room.

The of the pixels of the sensor surface 33 generated signals are from the X-ray machine 12 over the data line 14 to the computer 16 transmitted and there to an X-ray image, which in a memory, at 39 is indicated, is filed. In the computer also the rectification of the X-ray image takes place, further down in the sections 2 and 3 is explained in more detail.

Will the tubular insertion part 22 of the X-ray machine 12 into the oral cavity 34 a patient 36 introduced, as in particular in the 1 is recognizable, so pass through the x-rays 30 , which slows down the electrons at the point of impact of the target 28 were generated, the teeth and the adjacent periodontal ligaments and hit the X-ray detector 32 , The sensitivity of the pixels of the x-ray detector 32 detected X-ray depends on the amount and type, in particular the density, of the tissue that the X-rays on their way from the X-ray source 28 to the X-ray detector 32 have passed through.

By suitable design of the X-ray source 28 will ensure that the x-rays 30 both in the vertical direction (sectional plane of the 1 ) as well as in the horizontal direction (sectional plane of the 2 ) cover an angle that allows complete fluoroscopy of all teeth 38 and the associated periodontal apparatus of the patient. On the sensor surface 33 of the X-ray detector 32 Thus, a panorama-like picture emerges of the X-rays 30 penetrated tissue. Because the X-ray source 28 is approximately point-shaped and is relatively close to the tissue to be screened, obeys that on the sensor surface 33 in a fluoroscopic image resulting image of the rules of central projection.

This will be explained below with reference to the 3 to 6 explained in more detail.

2. General information on image formation

In the 3 is a cube-shaped grid 39 shown by a presumed as a point source of radiation 40 is illuminated. On an image plane 42 emerges from the shadows of the grid 39 a picture 139 according to the rules of central projection. So, for example, stays in the picture 139 obtain the parallelism of lines which, as assumed here, are arranged in planes which are parallel to the image plane 42 run. For three of the front corners of the grid 39 Projection rays are indicated by dashed lines and for the three corners behind it by dotted lines.

As you can see in the back view on the right side of the 3 can recognize, is the radiation source 40 concerning the grid 39 not centered but slightly offset to the lower left. Due to this staggered arrangement, this is on the image plane 42 resulting image 139 distorted. For a viewer of the picture 139 it is due to this distortion z. B. difficult to judge if the grid 39 the shape of a cube or not. Such Appraisal is only possible if the picture 139 arises from a perspective known to the viewer and particularly suitable for an assessment.

Such a known perspective is in the 4 shown. Here it is assumed that the radiation source 40 ' exactly on a central axis of the grid 39 that is, located on a line which is the centers of two opposite faces of the grid 39 interspersed (see rear view on the right edge of 4 ). The picture 139 ' now appears undistorted to the viewer, as it is the regularity of the grid 39 reproduces.

How to easily in the 1 and 2 also recognizes the image that is on the sensor surface 33 of the X-ray detector 32 when examining the teeth 38 arises, generally distorted. This is mainly because of how, in the 2 can recognize the teeth 38 not on a circular arc around the X-ray source 28 around, but on a curve that is difficult to approximate by a circular arc. Therefore, the projection ratios are all teeth 38 different on one half of a row of teeth. Accordingly, that too is on the sensor surface 33 of the X-ray detector 32 The resulting image is distorted, with the distortion continuously changing across the area of the image.

For the doctor, who is to make a dental or orthodontic diagnosis based on such a distorted image, it is difficult to mentally reverse that distortion when looking at the obtained X-ray image. It is particularly difficult or even impossible to correctly assess the proportions of the structures shown on such a distorted X-ray image.

It would be ideal for the doctor if for every tooth 38 his picture would appear taken under the same perspective. This may be, for example, a central perspective, as in the 4 is shown. However, a parallel perspective as it arises when the radiation source comes into consideration comes into consideration 40 far (ideally infinitely far) from the grid 39 or any other object is removed. Is the front surface of the grid 39 For example, perpendicular to the propagation direction of the rays, so are the images of the front and the rear edges of the grid in parallel projection 39 one above the other. Such a parallel perspective, the doctor knows, for example, of common panoramic photographs in which the X-ray source behind the head (and thus relatively far away from the teeth) is driven around the patient and an X-ray film or other X-ray detector is exposed through a wandering slit.

Do you know that in the 3 shown picture 139 of the grid 39 as well as the relative position of the image plane 42 to the radiation source 40 but that does not mean that the shape of the grid is yet to be understood 39 close back. The 5 shows this with the example of a warped lattice 41 : With otherwise the same projection ratios, ie position of the radiation source 40 and the picture plane 42 , is the projected image 141 not from the picture 139 of the undamaged lattice 39 from the 3 to distinguish.

3. Equalization - first embodiment

One way to get to the actual shape of the grid 39 to close and thus arrive at an equalized picture, is in the 6 shown. Here it is assumed that the location of a first object level 46 in which the source of radiation 40 turned four corners of the grid 39 are arranged relative to the radiation source 40 and the picture planes 42 is known. Does one know the position of the first object level 46 so can the arrangement of the front corners of the grid 39 be reconstructed in a simple way, by calculating from the image 139 outgoing rays with the radiation source 40 get connected. The puncture points at the object level 46 These rays are then the front four corners of the grid 39 firmly. In this way arises in the object plane 46 by rear projection of the picture 139 to the object level 46 an equalized archetype of the picture 139 ,

Strictly speaking, of course, the location of the second object level would have to be known, in which the of the radiation source 40 facing away from four corners of the grid 39 are arranged. However, the error that arises from estimating the distance of this second object plane to the first object plane is relatively small. Applied to the projections of the teeth 38 This means that one can easily determine the position of the second object plane by displacing the first object plane by the typical "thickness" of a row of teeth.

The 7 illustrates the corresponding conditions as in the recording of the x-ray image with in the 1 and 2 shown X-ray device 12 available. With 48 Here, an object surface is designated, whose three-dimensional shape has been set so that the X-ray source 28 facing surfaces of the teeth 38 to the object surface 48 lie approximately tangentially. Spaced behind is the sensor surface 33 of the X-ray detector 32 indicated. The object surface 48 thus corresponds to the object plane 46 and the sensor surface 33 the picture plane 42 in the presentation of the 6 ,

On the sensor surface 33 is an example of the picture 138 a tooth 38 indicated by projection as a result of X-ray fluoroscopy 30 on the sensor surface 33 arises. Calculate these on the sensor surface 33 lying points on the object surface 48 projected back, then an equalized archetype of the tooth arises 38 ,

This procedure requires that the coordinates of the sensor surface 33 relative to the location of the x-ray source 28 are known exactly. Furthermore, in this reference system, the position of the object surface must 48 be known. The position of the sensor surface 33 relative to the x-ray source 28 is with the X-ray machine 12 structurally fixed to each other. However, the location of the object surface is unknown at first 48 in this frame of reference, because the shape of the mandibular arch and the arrangement of the teeth held by it 38 may vary significantly from patient to patient. In particular, when the straightened X-ray image is also to be used to determine certain proportions of the teeth or the periodontal ligaments, it is generally not sufficient to have the same position of the object surface in all patients 48 or about a limited number of different object surfaces 48 equalization, from which one is selected according to the age of the patient.

Therefore, according to the invention, in this embodiment, the position of the object surface 48 metrologically determined by coordinates of the teeth 38 at several on the teeth 38 lying measuring points are determined by means of a measuring device. Possible measuring methods that are suitable in this context are described below with reference to the 8th to 12 described in more detail.

4. Measuring method

In the in the 8th In the embodiment shown, the measuring device is a triangulation sensor 50 in the oral cavity 34 of the patient 36 is introduced. Like the ones in the 9 shown front view of the triangulation sensor 50 shows, this has a light source 52 , For example, a laser diode or an LED, and a direction-resolved image sensor 54 on. The imager 54 For this purpose, typically includes a microlens and a CCD sensor.

The light source 52 and the imager 54 are on a crossbeam 56 arranged around a vertical axis 58 by means of a small servomotor (not shown) relative to a longitudinal member 60 is rotatable. In addition, the cross member 56 around a horizontal axis 61 with the help of another servomotor (also not shown) tiltable. In this way, that of the light source 52 generated light beam by pivoting about the vertical axis 58 and the horizontal axis 61 according to a defined scanning pattern via the to the triangulation sensor 50 pointing inner surfaces of the teeth 38 be guided. This results in a grid-like arrangement of measuring points whose coordinates can be accurately determined by triangulation relative to each other.

To these coordinates in relation to the X-ray machine 12 to put, is the side member 60 the triangulation sensor 50 with a bite bar 62 provided on its underside with a notch into which the lower incisors of the patient 36 can intervene. Even if the introduction part 22 of the X-ray machine 12 with a corresponding bite bar 63 provided by the triangulation sensor 50 obtained results on the position of the incisors of the patient 36 , which serve as a reference, spatially to the X-ray machine 12 be correlated.

The 10 and 11 show in similar representations as the 8th respectively. 9 an intraoral 3D stereoscopic camera used as a measuring device to determine the coordinates on the teeth. The total with 64 designated 3D camera includes two intraoral cameras 66 . 68 that, as in the 11 recognizable, on a common cross member 70 are arranged. The crossbeam 70 is at the end of a side member 72 attached, which at its underside again with a Aufbisssteg 74 is provided. In the area where the two intraoral cameras 66 . 68 overlapping images, the distance between the intraoral cameras can be determined by means of image processing (eg, by photogrammetric methods) 66 . 68 on the one hand and the recorded teeth 38 on the other hand.

In a modified measurement method, only the intraoral camera 66 used. The other intraoral camera 68 is replaced by a light source, which is provided with a mesh panel and a regular light grid 69 on the teeth 38 can project, as it is in the 12 is shown. Will this regular light grid 69 on teeth 38 projected, so takes the intraoral camera 66 a picture on how it is in the 13 is shown by way of example. As a result of the curvature of the teeth 38 the originally straight lines of light are also curved. The distance between the light lines is a measure of the distance of the teeth 38 to the intraoral camera 66 , By evaluating the distorted light line image, as shown in the 13 can also be shown a surface relief of the teeth 38 be won.

The 14 shows in a plan view of another measuring device with which the coordinates of lying on the teeth measuring points can be measured. The measuring device 73 has a side rail 72 on, which is dimensioned so that it enters the oral cavity 34 of the patient 36 introduced can be. On the side member 72 is a detector latch 76 arranged on the multiple detector elements 78 , For example, photodiodes, are arranged parallel to each other. Each detector element 78 is a cylindrical sleeve 80 associated, which causes only substantially parallel to the longitudinal axis of the sleeve 80 incident light from the detector elements 78 can be detected. The detector elements 78 thus form together with the pods 80 Directional optical sensors.

The detector latch 76 in turn carries a laser latch 82 , the several juxtaposed laser diodes 83 includes. The laser diodes 83 of the laser bar 82 are controlled in the measurement so that they at short intervals a laser beam 84 produce. As a result of the directional characteristic of the detector elements 78 can only certain detector elements 78 that from the teeth 38 detect reflected laser light. In the 14 this is for two detector elements 78 indicated by dashed lines.

Triangulation can then determine the distance between the teeth 38 relative to the measuring device 73 be determined. At the measuring device 73 is thus the pivoting head of the in the 8th and 9 shown triangulation sensor 50 replaced by a fixed array of multiple light sources and multiple detectors.

5. Equalization - second embodiment

A second embodiment of the invention will be described below with reference to FIG 15 explained.

First, reference should again be made to the 3 to 6 , As already mentioned above in connection with the 6 has been explained, can be derived from a distorted picture 139 reconstruct the undistorted archetype if the location of the object plane 46 is known. However, an equalization is possible even if at least part of the object, here the cube 39 The shape is known without its location relative to the image plane 42 and to the radiation source 40 knows exactly. In doing so, one exploits the fact that the transformation rule, which mathematically describes the equalization or equalization, can be assumed to be the same for smaller objects in a good approximation. With a tooth this can be assumed with good approximation; So if you know how to equalize the crown, you can equalize the neck of the tooth with the same transformation rule.

In the 15 For example, the steps performed for equalization in this embodiment are shown separated by arrows.

The starting point is the distorted X-ray image taken by the X-ray detector. In the 15 is such an x-ray image with 90 designated; for the sake of simplicity, only the pictures are 138 two teeth 38 shown.

In a next step, the X-ray image is taken 90 an edge image 92 the teeth 38 which is done using known edge detection algorithms.

Subsequently, the on the x-ray image 90 recognizable teeth 38 measured. The measurement of the teeth gives a surface relief 94 that in the 15 through curved lines 96 on teeth 38 is indicated. The surface relief 94 is now displayed from a predetermined target perspective. This desired perspective can be obtained from the X-ray examination system 10 fixed, but also freely selectable by an operator. The desired perspective can be determined individually for individual teeth or groups of teeth, so that the rectified X-ray image is composed of a plurality of partial images, which appear to be taken from different perspectives and are composed without gaps to form a panoramic image. In particular, a centrally centered central perspective, as used in the US Pat 4 is implied, or a parallel perspective. In the 15 it was assumed that the surface relief 94 already shown in the desired Sollperspektive.

On this representation of the surface relief 94 now become points indicated by crosses 98 established. This determination is preferably made automatically by the surface relief shown in the desired perspective 84 is subjected to edge detection and then characteristic points of the edges, such as corners or strong bends, as vertices 88 to be selected.

To these bases 88 will now be corresponding points 98 ' on the edge picture 92 visited, from the x-ray 90 was derived.

In a next step, a transformation rule is defined, which defines the points 98 ' on the bases 98 converts. The term "transformation rule" is understood here to mean any collection of rules with which a linear or nonlinear distortion or equalization can be described for a group of pixels. If in the 15 the transformation rule is referred to as matrix T, this therefore represents a rough simplification, because with a matrix alone, the transformation of a larger group of pixels in general will not be described.

The transformation rule will now apply to the entire X-ray image 90 applied, whereby the teeth shown therein 138 ' be rectified and displayed so that they appear taken from the desired Sollperspektive. The result is an equalized X-ray image 100 in which also the tooth roots and tooth necks, which were not recognizable during the measurement, appear from the desired desired perspective.

This process can be repeated for each individual tooth or groups of teeth that can apply the same transformation protocol.

6. Common procedural steps

The 16 shows in the form of a flow chart essential steps of the method according to the invention, which are common to both embodiments.

In a step S1, the X-ray source becomes 28 in the oral cavity 34 of the patient 36 arranged.

In a second step S2, the X-ray detector 32 arranged so that it extends from the outside around the patient's mandibular arch 36 extends around.

In a third step S3, the teeth become 38 of the patient 36 X-rayed.

In a fourth step S4, the focus on the X-ray detector 32 detected incident X-ray.

In a fifth step S5, a digital X-ray image is determined on the basis of the X-ray detector 32 detected X-ray generated.

In a sixth step S6, coordinates of several on the teeth 38 lying measuring points using a measuring device, for example, the triangulation sensor 50 , the 3D camera 64 or the measuring device 73 , measured.

In a seventh step S7, the digital X-ray image generated in step S5 is equalized using the coordinates measured in step S6.

7. Further embodiments of measuring devices according to the invention

With the in the 8th to 14 The measurement devices shown can be the patient's teeth 36 either before or after the X-ray image is taken. Simultaneous measurement is hardly practicable, since the side member 60 or 72 with the components attached thereto only at the cost of greater difficulty in addition to the insertion 22 of the X-ray machine 12 into the oral cavity 34 of the patient 36 can be introduced.

In the following, measuring devices are described which make it possible to measure and to examine the teeth 38 simultaneously or in such a way that no reconstructions of the X-ray machine, eg. B. a pivoting away certain parts of the measuring device, are required. Simultaneously performing the survey and fluoroscopy reduces the susceptibility to errors, because the simultaneity ensures that the survey is done in the condition in which the patient's teeth are illuminated. The longer the time span between the two processes and the more steps (eg removal of parts of the measuring device, taking a new bite position) have to be made during this period, the higher the likelihood that errors will occur, such as the patient inadvertently occupies another than the desired Aufbissposition or he initially occupies this, but then leaves again unintentionally by small jaw movements.

However, a simultaneous measurement requires that no or at least no parts of the measuring device impermeable to X-rays are arranged in the beam path of the X-ray radiation such that the images of these parts cover the images of the teeth and other structures of interest on the recorded X-ray images. In the embodiments of measuring devices described below, this is achieved in different ways.

The 17 shows in an vertical section an embodiment of an X-ray device 12 in which two of the in the 10 and 11 shown stereoscopic 3D cameras at the distal end of the insertion 22 are attached. The in this embodiment with 64a . 64b designated 3D cameras each include two intraoral cameras 66 . 68 like this in the 11 is shown (in the vertical section of the 17 are only the intraoral cameras turned to the viewer 66 visible). The two 3D cameras 64a . 64b are so far behind the X-ray source 28 attached them to the spread of x-rays towards the teeth 38 of the patient 36 do not hinder. By this arrangement behind the X-ray source 28 can the teeth 38 simultaneously illuminated and with the help of the two 3D cameras 64a . 64b be measured.

Because the insertion part 22 in comparison to the side member 72 has relatively large dimensions, can not do any of the two 3D cameras 64a . 64b both rows of teeth of the patient 36 be detected optically at the same time. Therefore, in this embodiment, two independent 3D cameras 64a . 64b each measuring the row of teeth lying on its side. Alternatively, it is considered, only a 3D camera 64a provide that about the longitudinal axis of the insertion 22 is pivotable about 180 °, so that the two rows of teeth sequentially from a 3D camera 64a can be measured.

In the intraoral cameras 66 . 68 that part of the 3D cameras 64a . 64b are, can be endoscope cameras. This has the advantage that the intraoral cameras 66 . 68 very small dimensions may have, reflecting the inclusion of the 3D cameras 64a . 64b into the oral cavity of the patient 36 facilitated. The of the intraoral cameras 66 . 68 recorded images can z. B. via a fiber optic to the main body 20 of the X-ray machine 12 be transmitted. Free-beam transmission using angle optics is also considered for this purpose. The intraoral cameras 66 . 68 however, they can also be designed as so-called video endoscopes, in which electronic image sensors are arranged in the receiving heads of the intraoral cameras. The image transfer to an evaluation, the z. B. as in the computer 16 executable software can be formed, then takes place not on optical, but on electronic way. The same applies to the intraoral cameras in the 10 and 11 shown embodiment.

In the 17 is at the reference number 102 a marking object is indicated, which is impermeable to X-rays and in the illustrated embodiment has the shape of a small ball, which has a short foot on the insertion part 22 is attached. The marking object 102 is arranged so that it is not in the beam path of X-rays, the teeth or other structures of interest in the jaw area of the patient 36 pass. This covers the image of the marker object 102 not the pictures of the structures of interest. Because the patient 36 keep his mouth open anyway, to a part of the introduction part 22 into his mouth 34 to be able to record, remains on the X-ray image always a central strip between the two illustrated rows of teeth on which the marker object 102 should preferably appear.

The provision of such a marking object 102 is particularly advantageous if it is not a CCD or a CMOS sensor in the X-ray detector, but the X-ray detector is an interchangeable image carrier, for. B. a storage film or an X-ray film having. With such interchangeable image carriers, it may occasionally happen that the image carrier is not positioned exactly in a suitable receptacle. Since the equalization invention requires that the position of the X-ray detector 32 relative to the x-ray source 28 As is well known, such misalignments of an interchangeable image carrier can result in the equalization being erroneously performed and the teeth 38 of the patient 36 thus not appear correctly on the rectified X-ray image.

With the help of the marking object 102 , which is also located in the beam path of the X-ray and is displayed on the removable image carrier, the computer 16 from the location of the image of the marker object 102 on the removable image carrier, the position of the image carrier relative to the X-ray source 28 determine. Softens the image of the marker object 102 from its nominal position on the image carrier, the image carrier was not exactly aligned in its recording during the X-ray recording. From the displacement of the actual image relative to the target position of the image, the computer 16 then determine the amount and direction of the misalignment and correct the remaining pixels accordingly. In order to increase the accuracy of the correction, it is also possible to provide a spatially extended marking object or a plurality of distributed marking objects.

The 18 shows in an horizontal section an embodiment of an X-ray device according to the invention 12 in which the measuring device is not intraoral, but extraorally between the teeth 38 of the patient and the x-ray detector 32 is arranged. The measuring device in this embodiment comprises four triangulation sensors 50a . 50b . 50c . 50d whose measuring apertures are each indicated by dashed lines. The triangulation sensors 50a to 50d are on a carrier 104 attached, in turn, on the insertion part 22 is set in a manner not shown.

The 19 shows the measuring device in a front view at the height of the line XIX-XIX, for better clarity, the X-ray detector 32 just indicated with its outline and the bracket 31 , with which the X-ray detector 32 at the main part 20 of the X-ray machine 12 is attached, not shown at all. As you can see in this illustration, the carrier is 104 so aligned in the vertical direction that both the wearer 104 itself as well as the triangulation sensors carried thereby 50a to 50d extend along a space between the two rows of teeth of the patient 36 remains. The height of this gap is essentially due to the diameter of the insertion part 22 and the dimensions of the bite bars 63 established.

As a result of this arrangement of the measuring device in the space between the two rows of teeth, the measuring device is indeed imaged with the X-ray image, but their image covers neither the teeth 38 even other structures of the mandibular arch that may be of interest. Nevertheless, it is possible through the central arrangement between the two rows of teeth, this with the triangulation sensors 50a to 50d at the same time optically to measure.

As in particular in the 18 can recognize, extends the carrier 104 not over the entire length of the patient's mandibular arch. This is due to the fact that in an extra-oral optical measurement, even if the patient's lips are pushed up or down, the molars of the patient can not be measured, since they are covered by the cheeks. However, the position of those molars can be extrapolated with sufficient accuracy, it being possible to resort to statistical data of patients of the same age and gender or other typifying parameters.

The 20 and 21 show in the 18 and 19 Similar representations of an embodiment of an X-ray device according to the invention 12 in which the triangulation sensors 50a to 50d also extraorally, but on a side facing away from the patient back of the X-ray detector 32 are arranged. So that the triangulation sensors 50a to 50d for the optical measurement have a visual connection to the front region of the two rows of teeth of the patient, has the X-ray detector 32 a central strip-shaped opening 105 which is located in the plane between the two rows of teeth, in which also the triangulation sensors 50a to 50d in the 18 and 19 shown embodiment are arranged. This will ensure that X-rays pass through the opening 105 meets, not before teeth 38 or other interesting structures of the mandibular arch has been examined.

Of course it is possible the opening 105 to the two shorter transverse sides of the X-ray detector 32 to extend so that it is divided into two halves, which are spaced apart.

The 22 shows in a vertical section an embodiment of an X-ray device according to the invention 12 in which the measuring device reflectors 106a . 106b that is between the patient 36 and the X-ray detector 32 are arranged. The measuring device has in this embodiment for each row of teeth on two 3D cameras, each comprising two individual cameras, of which in the 22 one for each row of teeth and with 66a respectively. 66b is designated. The cameras 66a . 66b are at the two upper and lower longitudinal edges of the X-ray detector 32 arranged and are thus located outside the beam path of the X-ray.

The reflectors 106a . 106b on the other hand, in the beam path, there are X-rays, which are also the teeth 38 of the patient 36 passes. Therefore, the reflectors need 106a . 106b be at least largely transparent to X-ray. This also applies to feet 110a . 110b on which the reflectors 106a . 106b at the insertion part 22 support. For a wearer of the reflectors 106a . 106b and the feet 110a . 110b comes as a material thus, for example, plastic into consideration. A reflective coating of the reflectors applied to the supports 106a . 106b For example, can be made of aluminum, the X-ray only weakly absorbed.

In the illustrated embodiment, the carrier of the reflectors 106a and 106b flat plates that stretch across the entire width of the patient's mouth 36 extend. This allows the cameras 66a . 66b an undistorted image of the teeth of the patient lying in the region of the mouth opening 36 take up. So that the lips of the patient 36 These teeth do not obscure the X-ray detector 32 two likewise strip-shaped bearing surfaces 108a . 108b attached, over which the lips of the patient are pushed and which consist of a material that is permeable to both visible light and X-rays, z. Glass.

The 23 and 24 show in the 18 and 19 Similar representations of an embodiment of an X-ray device according to the invention 12 , whose measuring device has an upper and a lower contour measuring arc 110a respectively. 110b includes. Each contour measuring arc 110a . 110b in turn has several plant members 112 on that over joints 114 connected to each other. The joints 114 allow thereby a deflection of the plant members 112 perpendicular to a measuring plane, in which the contour measuring arcs 110a . 110b each extend.

As seen in the front view of the 24 can recognize at the height of the line XXIV-XXIV is any joint 114 an angle encoder 116 assigned. This generates an electrical output signal as a function of the angle between the abutment members 112 is formed, which over the relevant joint 114 connected to each other. The electrical output signals of the angle encoders 116 be via an unillustrated electrical signal line the computer 16 fed. If the electrical signal lines from an X-ray only weakly absorbing material such as Aluminum, so they can be at the teeth 38 facing away from the back of the plant members 112 be guided along. Otherwise, it is possible to guide the signal lines in the space between the rows of teeth of the patient.

The plant members 112 as well as the joints 114 consist of a permeable to X-ray material, eg. B. plastic. How to get in the 24 can recognize, are the angle encoder 116 so at the end of the joints 114 arranged so that they are in the space between the two rows of teeth of the patient during the measuring process. The angle encoders 116 may therefore contain materials that are impermeable to X-rays.

The respective middle contact element of each contour measuring arc 110a . 110b is over one of the footbridges 118a respectively. 118b (please refer 24 ) firmly with the insertion part 22 of the X-ray machine 12 Connected and represents for the incisors of the patient a stop. If the incisors of the patient on the central abutment member 112 strike, the remaining investment links 112 so with the help of the joints 114 pivoted that to the teeth 38 pointing contact surfaces 120 the plant members 112 be brought into contact with the row of teeth of the patient. The adjustment of the joints 114 occurring angle changes are from the angle encoder 116 captured and sent to the computer 16 transmitted. This then determines on the basis of the angle changes the shape of the two contour arcs 110a . 110b from which finally the positions of the teeth 38 can be derived.

The 25 and 26 show in the 23 and 24 Similar representations of an embodiment of an X-ray device according to the invention 12 , in whose measuring device the contour measuring arcs 110a . 110b each a plastically deformable carrier 122 whose, to the teeth 38 facing inner surface as contact surfaces 120 are formed. Every carrier 122 carries several absorption bodies 124 that over feet 126 at the respective carrier 122 are attached. The feet and the carrier 122 consist of an X-ray transparent material, while the absorption body 124 , which may for example have the shape of small balls, almost completely absorb X-rays. The feet 126 are dimensioned so that the absorption body 124 are arranged in the space between the rows of teeth, as shown in the 26 is recognizable. As a result, when the teeth are illuminated 38 the absorption bodies from the X-ray detector 32 but their images are not the images of the teeth 38 to cover.

Also in this embodiment, the contour arcs 110a . 110b over footbridges 118a . 118b at the insertion part 22 set so that the middle section of the contour arcs 110a . 110b each serves as a stop for the rows of teeth of the patient. If the carrier 122 are shaped so that they can be plugged self-locking on the rows of teeth, can on the bars 118a . 188b be waived. The plastically deformable carrier 122 are now bent so that their contact surfaces 120 in contact with the teeth 38 come, like this in the 25 is recognizable. Now an X-ray of the teeth 38 made, the pictures of the absorption bodies appear on the x-ray picture 124 as two rows of dots in the space between the rows of teeth. From the size and location of the points can the computer 16 on the location of the absorption body 124 during fluoroscopy of the teeth 38 shut down. In this embodiment, thus eliminating the burden of one in the contour arcs 110a . 110b integrated sensors and the necessary wiring.

8. Bite sensor

In many cases, just the coordinates of a few measuring points on the teeth can suffice 38 of the patient 36 to measure, for. B. the coordinates of measuring points on the cutting edges of the incisors. Are these coordinates relative to the location of the x-ray source 28 and the X-ray detector 32 As is known, an equalization of the X-ray images can be carried out if the position of the remaining teeth is extrapolated on the basis of typical mandibular arch forms.

Often it will be desired, the location of the X-ray source 28 in the oral cavity 34 of the patient 36 Free to determine, for optimal imaging of the teeth 38 to obtain. In principle, it would be conceivable to provide a plurality of bite notches on the insertion part, of which a suitable bite notch is selected for the receptacle. However, it is relatively expensive to ensure that the incisors of the patient actually intervene in the desired bite notch and do not leave this position until they are illuminated. Because with every unintentional opening of the mouth, the bite is lost and must be re-established.

In the following, various embodiments of Aufbisssensoren will be described, in their use, the difficulties described above can not occur. The bite sensors make it possible to measure the position of the incisors of the patient with high accuracy and extremely reliable. As a result, incorrect exposures, in which the patient has left the desired Aufbissposition or not even properly taken, largely excluded.

The 27 shows a first embodiment of a Aufbisssensor in a horizontal intersection. The total with 130 designated Aufbisssensor 130 has a tubular and closed at its distal end sleeve 132 on, on the likewise tubular insertion part 22 pushed on the end and locked in a manner not shown. In the wall of the sleeve 132 are formed as a plurality of piezoelectric pressure sensors in the longitudinal direction of the sleeve 132 arranged one after the other, what follows with reference to the 28 is explained in more detail.

The 28 shows an enlarged section of the 134 designated wall of the sleeve 132 , The sleeve wall 134 has over a section of a few centimeters an elastic outer wall 136 and a solid inner wall 138 on, between those with 140 designated piezo elements are arranged. Each piezo element 140 is designed as a so-called stacked piezoelectric element, in which between three metal electrodes two piezoelectric crystals 142a . 142b Sandwich-like are arranged. One of each of the two outer metal electrodes is located on the elastic outer wall 136 on, while the other metal electrode in a manner not shown on the solid inner wall 138 supported.

Bites the patient with an incisor 38 on the sleeve 132 , so the bite pressure generated is over the elastic outer wall 136 on those piezo elements 140 transferred, which are located near the Aufbissstelle. The on the relevant piezoelectric element 140 applied pressure generates an electrical signal via signal lines 144 to the computer 16 is transmitted. From the height and the assignment of the signal to the relevant piezo elements 140 can the computer 16 close to the place where the tooth is 38 on the elastic outer wall 136 of the bite sensor 130 is applied. Along the longitudinal direction of the bite sensor 130 In this way, the coordinates of the abutment surfaces of the incisors can be measured with an accuracy which, in this embodiment, depends on the number of piezoelements provided longitudinally per unit length 140 depends. The longitudinal direction of the bite sensor 130 in this embodiment coincides with an insertion direction along which the insertion part 22 together with the Aufbisssensor pushed on it 130 into the oral cavity 34 of the patient 36 is introduced.

The part of the sleeve wall 134 who in the 28 The section shown diametrically opposite and serves to measure the Aufbissflächen the lower incisors, has the same structure and the same function.

The piezo elements 140 in the 27 and 28 shown embodiment can also be replaced by other pressure sensors. It is also possible to replace the pressure sensors with proximity sensors. In this way, additionally or exclusively, the position of the patient's lips 36 along the direction of insertion, as the lips of the patient may be the bite sensor with the mouth slightly open 130 do not touch at all.

The 29 shows in sections in one of the 28 ajar representation of an embodiment of a Aufbissensors, in which a plurality of proximity sensors along the insertion direction behind the other in the sleeve wall 134 arranged as capacitive proximity sensors 146 are formed. The outer wall 136 the sleeve wall 134 must not be deformable in this case, since the proximity sensors 146 only to approach, but not to respond to pressure from body tissue, so that at the same time the location of a lip 148 and a neighboring incisor 38 are detectable. The proximity sensors 146 can also be designed so that they only respond to the approach of water-containing tissue, so that the incisor 38 is not detected.

Also in this embodiment sets the density of the proximity sensors 146 in the insertion direction, the spatial resolution of Aufbisssensors 130 firmly. In the in the 28 and 29 illustrated embodiments, the spatial resolution can be increased if between electrical signals from adjacent piezoelectric elements 140 or proximity sensors 146 be generated, interpolated.

To achieve a spatial resolution, not necessarily several sensors must be arranged one behind the other. The 30 shows in sections in one of the 28 and 29 ajar representation of a sensor element of Aufbisssensors 130 as a linear potentiometer 150 is trained. That in the 30 only linearly shown linear potentiometer has a resistance surface extending along the insertion direction 152 and a parallel thereto at a close distance guided elastic electrode 154 on that together with the drag area 152 is connected in the manner of a voltage divider circuit. The required for a linear potentiometer movable tapping point is the linear potentiometer 150 where it creates where the elastic electrode 154 from a tooth 38 or the lip of the patient through an elastic outer wall 136 is deflected so far that the elastic electrode 154 on the resistance surface 152 is applied. The contact point represents the tapping point of the linear potentiometer. The position of the contact point along the insertion direction can then be derived from the measured voltage with high accuracy in a conventional manner.

The 31 shows in a to the 27 ajar representation of another embodiment of a Aufbisssensor 130 in which the sleeve 132 not fixed to the insertion part 22 is locked or otherwise fixed, but can be moved linearly on this, as shown in the 31 by a double arrow 162 is indicated. The sleeve 132 is at its top and bottom, each with a single bite notch 160a . 160b provided for intervention of the incisors of the patient 36 are provided. So that the patient can feel clearly, whether his incisors correctly in the bite marks 160a . 160b can intervene at their bottom with a tough and plastically deformable material, while the other surface of the sleeve 132 can be made of a smooth hard material. This is the sensory impression in the patient 36 for smaller jaw movements quite different depending on whether its incisors in the bite marks 160a . 160b engage or (inadvertently) next to it on the smooth hard surface of the sleeve 12 rest.

In the illustrated embodiment, the sleeve 132 with the help of a servomotor 164 displaced along its longitudinal direction. The servomotor 164 in turn is from the computer 16 driven. The control of the servomotor 164 takes place such that this is a desired distance between the bite notches 160a . 160b on the one hand and the X-ray source 28 on the other hand is given. This nominal distance can be in the computer 16 be calculated by a program to which patient-specific parameters such as age, sex or the like are supplied. The nominal distance can also directly with the help of suitable input means the computer 16 be specified. The servomotor 164 moves the sleeve 132 with the bite notches arranged thereon 160a . 160b so far that the desired nominal distance is reached. The servomotor 164 serves as a position sensor, allowing the computer 16 always the actual distance between the bite notches 160a . 160b and the X-ray source 28 is known.

For a regular calibration of the servomotor 164 To make unnecessary, the Aufbisssensor shown an additional position sensor 166 on, with which the position of the sleeve 132 relative to the insertion part 122 along the longitudinal direction is measurable. The position sensor 166 in this embodiment optically scans a rack 168 off, by a pinion 170 of the servomotor 164 is combed.

As on the sleeve 132 only one bite notch each 160a . 160b placed on the top or bottom, there is no risk that the patient 36 accidentally bites into a wrong bite notch or into another bite notch as may be the case with bite elements where multiple bite notches are spaced close to the top and / or bottom. This reliably ensures that the X-ray source 28 while transilluminating the patient's teeth 36 located exactly at the target position, for the optimal imaging of the teeth on the X-ray detector 32 is expected.

In a modification of the in 31 the embodiment shown is the servomotor 164 replaced by a locking device that can be manually or electrically operated. The position sensor 166 preferably outputs the measured position to a readily recognizable display device on which an operator measures the distance between the bite notches 160a . 160b on the one hand and the X-ray source 28 (or any other derived variable) can read. While his incisors in the bite marks 160a . 160b intervene, the patient moves 36 his head as long along the longitudinal axis of the insertion 22 until the desired distance appears on the display device. At this distance, then the locking device by the operator or by a command of the computer 16 pressed, causing the sleeve 132 determined and thus no longer in the direction of the double arrow 162 can be moved.

Claims (51)

Method for the production of straightened X-ray images for dental or orthodontic diagnostics, comprising the following steps: a) arranging (S1) an X-ray source ( 28 ) in the oral cavity ( 34 ) of a patient ( 36 ); b) arranging (S2) an X-ray detector ( 32 ) such that it extends from outside at least a part of the patient's dental arch ( 36 ) extends around; c) Examination (S3) of the teeth of the patient ( 36 ) with X-radiation; d) detection (S4) of the X-ray detector ( 32 ) incident X-radiation; e) generating (S5) a digital X-ray image on the basis of the X-ray radiation detected by the X-ray detector; characterized by the following further steps: f) measuring (S6) coordinates of several on the teeth ( 38 ) lying by means of a measuring device ( 50 ; 64 ; 73 ; 50a to 50d ; 106a . 106b . 66a . 66b ; 110a . 110b ; 130 ); g) equalizing (S7) the digital X-ray image using the coordinates measured in step f). A method according to claim 1, characterized in that in step f) the coordinates of the measuring points are determined relative to a reference point whose position relative to the X-ray detector ( 32 ) and the X-ray source ( 28 ) is known. Method according to claim 2, characterized in that the reference point is defined by a bite point of the patient ( 36 ). Method according to one of claims 2 or 3, characterized in that in step g) from the measured coordinates of the measuring points a between the X-ray source ( 28 ) and the X-ray detector ( 32 ) arranged object surface ( 48 ) and the rectified X-ray image by backprojection of the X-ray image onto the object surface ( 48 ) is determined. A method according to claim 1, characterized in that in step f) the coordinates of the measuring points are determined relative to each other, and that the step g) comprises the following further steps: ga) determining a desired perspective for the rectified X-ray image; gb) equalizing the X-ray image in such a way that the X-ray image appears from the desired perspective determined in step ga). Method according to Claim 2, characterized in that the step gb) comprises the following further steps: gba) generating an edge image ( 92 ) of the X-ray image ( 90 ) using an edge detection algorithm; gbb) deriving a three-dimensional surface relief ( 94 ) of the teeth from the coordinates obtained at the measuring points; gbc) representation of the surface relief from the desired perspective determined in step ga); gbd) Selection of vertices ( 98 on the surface relief depicted in step gbc) and assigning the support points to corresponding points ( 98 ' ) on the edge image generated in step gba) ( 92 ); gbe) deriving a transformation rule, which specifies the corresponding points ( 98 ' ) on the edge image ( 92 ) into the vertices selected in step gbd) ( 98 ) converted; gbf) applying the transformation rule to the digital x-ray image taken in step e) ( 90 ). A method according to claim 6, characterized in that the transformation rule contains a plurality of sub-rules that convert portions of the x-ray image. A method according to claim 7, characterized in that on each partial area a tooth ( 38 ) or multiple teeth are shown. Method according to Claim 6, characterized in that the assignment of the interpolation points ( 98 ) to corresponding points ( 98 ' ) is carried out automatically on the edge image generated in step gba), wherein - from the surface relief shown in step gbc) ( 94 ) an edge image of the surface relief is produced by means of edge detection, and wherein - corners or other characteristic support points are automatically selected according to predefinable selection criteria on the basis of the edge image. Method according to one of claims 5 to 9, characterized in that the desired perspective corresponds to a development of a row of teeth. Method according to one of the preceding claims, characterized in that the measuring device is an optical triangulation sensor ( 50 ) or an ultrasonic sensor is used. Method according to one of the preceding claims 1 to 10, characterized in that in step f) a plurality of overlapping camera images taken from different intraoral positions and derived therefrom, the coordinates of the measuring points. Method according to one of the preceding claims 1 to 10, characterized in that in step f) generates a light pattern on the teeth and this light pattern of optical sensors ( 78 . 80 ) is detected. Method according to one of the preceding claims, characterized in that for the measurement in step g) used light or sound waves by a in the X-ray detector ( 32 ) provided opening ( 105 ) before entering the measuring device ( 50a to 50d ) to meet. Method according to one of the preceding claims, characterized in that for the measurement in step g) used light or sound waves from a extraorally arranged and transparent to the X-ray reflector ( 106a . 106b ) before they are applied to a sensor ( 66a . 66b ) of the measuring device. Method according to one of the preceding claims, characterized in that a calibration step is carried out in which an X-ray image is taken without patients and pixel or area determined by which correction amounts the intensity must be changed in order to obtain a constant over the X-ray image intensity and that later generated X-ray images of teeth are corrected for their intensity taking into account the correction amounts. Method according to one of the preceding claims, characterized in that a) the X-ray detector ( 32 ) has an exchangeable image carrier, in particular a storage film or an X-ray film, that b) is a marking object ( 102 ) is in the beam path of the X-radiation which is imaged on the image carrier, and that c) from the position of the image of the marking object ( 102 ) on the image carrier, the position of the image carrier relative to the X-ray source ( 28 ) is determined. Method according to one of the preceding claims, characterized in that a) the X-ray detector ( 32 ) has an exchangeable image carrier, in particular a storage film or an X-ray film, and carries a plurality of markings which are transmitted to the digital X-ray image when the image carrier is read, and b) from the position of the markings on the digital X-ray image detected and mathematically inhomogeneities of the image carrier be rectified the equalization. Method according to one of the preceding claims, characterized in that the steps c) and f) are carried out simultaneously. A system for the preparation of rectified X-ray images for dental or orthodontic diagnostics, comprising: a) an oral cavity of a patient ( 36 ) mountable X-ray source ( 28 ); b) an X-ray detector ( 32 ) which can be arranged in such a way that it at least extends around a part of the patient's mandibular arch from the outside ( 36 ) and with which on the X-ray detector ( 32 ) incident X-radiation is detectable; c) a digital memory ( 39 ) for storing an X-ray image generated by the X-ray detector ( 32 ) after examining the teeth of the patient ( 36 ) has been included; characterized by d) a measuring device ( 50 ; 64 ; 73 ; 50a to 50d ; 106a . 106b . 66a . 66b ; 110a . 110b ; 130 ) for measuring coordinates of a plurality of measuring points located on the teeth; e) an equalization device ( 16 ) set up for computer-aided equalization of the X-ray image using the coordinates measured in step f). System according to claim 20, characterized in that the measuring device is adapted to determine in step f) the coordinates of the measuring points relative to a reference point whose position relative to the X-ray detector ( 32 ) and the X-ray source ( 28 ) is known. System according to claim 21, characterized in that the reference point is defined by a bite point of the patient ( 36 ). System according to one of claims 20 to 22, characterized in that the equalization device is adapted to in step g) from the measured coordinates of the measuring points a between the X-ray source ( 28 ) and the X-ray detector ( 32 ) arranged object surface ( 48 ) and the rectified X-ray image by back projection of the X-ray image on the object surface ( 48 ) to investigate. System according to claim 20, characterized in that the measuring device is adapted to determine in step f) the coordinates of the measuring points relative to each other, and that the equalizing means is adapted to equalize the X-ray image such that the X-ray image taken from a predetermined desired perspective appears. System according to claim 24, characterized in that the equalization device is adapted to perform the following steps: - generating an edge image ( 92 ) of the X-ray image ( 90 ) using an edge detection algorithm; - deriving a three-dimensional surface relief ( 94 ) of the teeth from the coordinates obtained at the measuring points; - Representation of the surface relief from the given desired perspective; - Selection of bases ( 98 ) on the surface relief and assigning the vertices to corresponding points ( 98 ' ) on the edge image ( 92 ); Derive a transformation rule which contains the corresponding points ( 98 ' ) on the edge image ( 92 ) into the selected interpolation points ( 98 ) converted; - Apply the transformation rule to that in the digital memory ( 39 ) stored X-ray image ( 90 ). System according to one of claims 20 to 25, characterized in that the measuring device is an optical triangulation sensor ( 50 ) and / or an ultrasonic sensor and / or a 3D camera ( 64 ). System according to one of claims 20 to 26, characterized in that the measuring device is a light source ( 82 ), with which a light pattern ( 69 ) on the inner or outer surfaces of the teeth ( 38 ) is projectable, and an optical sensor ( 66 ; 78 . 80 ) for detecting the light pattern. System according to one of claims 20 to 27, characterized in that the Measuring device ( 50 ; 64 ; 73 ; 50a to 50d ; 106a . 106b . 66a . 66b ; 110a . 110b ; 130 ) is arranged for an arrangement in which parts of the measuring device, which are impermeable to X-radiation, are not penetrated by X-rays which previously had teeth ( 38 ). System according to one of claims 20 to 28, characterized in that the measuring device ( 50 ; 64 ; 73 ; 130 ) is set up for an intraoral arrangement. System according to one of claims 20 to 28, characterized in that the measuring device ( 50a to 50d ; 106a . 106b . 66a . 66b ; 110a . 110b ) is arranged for an extraoral arrangement. System according to claim 30, characterized in that parts ( 50a to 50d ; 116 ; 124 ) of the measuring device, which are impermeable to X-ray radiation, can be arranged in a plane which extends when the patient's mouth is open ( 36 ) extends between its upper and lower rows of teeth. System according to one of claims 30 or 31, characterized in that the measuring device ( 50a to 50d ; 106a . 106b ; 110a . 110b ) at least partially for an arrangement between the patient ( 36 ) and the X-ray detector ( 32 ) is set up. System according to one of claims 30 to 32, characterized in that the measuring device is a contour measuring arc ( 110a . 110b ), which extends in a measuring plane and bearing surfaces ( 120 ) for engagement with a row of teeth of the patient, wherein the shape of the contour measuring arc ( 110a . 110b ) is adjustable in the measuring plane to the contact surfaces ( 120 ) in contact with the row of teeth, and the measuring device means ( 114 . 116 ; 124 ) for determining the shape of the contour measuring arc. System according to claim 33, characterized in that the means sensors ( 116 ) included in the contour measuring arc ( 110a . 110b ) are integrated. System according to claim 34, characterized in that the contour measuring arc ( 110a . 110b ) several plant members ( 112 ), which by joints ( 114 ) and that through the sensors ( 116 ) the deflections of the joints ( 114 ) can be determined. System according to one of claims 33 to 35, characterized in that the means with the contour measuring arc ( 110a . 110b ) associated absorption body ( 124 ), which are opaque to the X-ray radiation and arranged such that X-ray radiation emitted by the absorption bodies ( 1214 ), not previously teeth ( 38 ), and that the position of the absorption bodies ( 124 ) from the equalizer ( 16 ) can be determined. System according to one of claims 33 or 36, characterized in that the contour measuring arc ( 110a . 110b ) a plastically deformable carrier ( 122 ). System according to one of claims 20 to 31, characterized in that the measuring device ( 50a to 50d in 20 and 21 ) at least partially for placement on one of the patient ( 36 ) facing away from the back of the X-ray detector ( 32 ) is set up. System according to claim 38, characterized in that the X-ray detector ( 32 ) an opening ( 105 ) arranged such that X-ray radiation passing through the opening ( 105 ), not previously teeth ( 38 ), and that the measuring device ( 50a to 50d ) behind the X-ray detector ( 32 ) in the region of the opening ( 105 ) is arranged that the opening ( 105 ) a visual contact between the measuring device ( 50a to 50d ) and the teeth ( 38 ) allows. System according to one of claims 20 to 32 and 38, characterized in that the measuring device comprises a reflector ( 106a . 106b ), which is responsible for an arrangement between the patient ( 36 ) and the X-ray detector ( 32 ) and is reflective for light or sound waves and permeable to X-radiation. System according to one of claims 20 to 28, characterized in that the measuring device is a spatially resolving Aufbisssensor ( 130 ), by which the coordinates of a contact surface of a ( 38 ) Tooth and / or lip ( 148 ) of the patient ( 36 ) are measurable at least along one direction. System according to claim 41, characterized in that the bite sensor comprises a bite element ( 132 ), along an adjustment direction ( 162 ) displaceable and with a bite notch ( 160a . 160b ), and a position sensor ( 164 . 166 ), with which the position of the bite element ( 132 ) along the adjustment direction ( 162 ) is measurable. System according to claim 42, characterized in that the bite sensor comprises a motor ( 164 ) for displacing the bite element ( 132 ) having. System according to claim 43, characterized in that the motor is a servomotor ( 164 ), which also serves as a position sensor. System according to one of claims 42 to 44, characterized in that the bite element ( 132 ) has a sleeve-shaped base body, which on an insertion part ( 22 ), which the X-ray source ( 28 ), along a longitudinal axis of the insertion part ( 22 ) is arranged displaceably. System according to claim 41, characterized in that the bite sensor ( 130 ) at least one sensor element ( 140 ; 146 . 150 ) and a carrier ( 132 ), which carries the at least one sensor element and at least partially into the oral cavity ( 34 ) of the patient ( 36 ) is insertable, wherein at least the coordinates of the contact surface along a reference direction can be determined by the at least one sensor element. System according to claim 46, characterized in that the at least one sensor element comprises a plurality of successively arranged pressure or proximity sensors ( 140 ; 146 ) whose size and arrangement determines the spatial resolution with which the coordinates of the contact surface can be measured. System according to claim 46, characterized in that the at least one sensor element is a linear potentiometer ( 150 ), which is a resistive surface ( 152 ) and an elastic electrode ( 154 ), wherein a movable tapping point of the linear potentiometer ( 150 ) is producible where the elastic electrode ( 154 ) by a tooth ( 38 ) and / or the lip ( 148 ) of the patient ( 36 ) is deflected so far that the electrode ( 154 ) on the resistance surface ( 152 ) is present. System according to one of Claims 46 to 48, characterized in that the support ( 132 ) on an insertion part ( 22 ) which is the X-ray source ( 28 ) contains. System according to claim 49, characterized in that the carrier is a sleeve ( 132 ), which is on the insertion part ( 22 ) is postponed. System according to one of claims 20 to 50, characterized in that the X-ray detector ( 32 ) comprises an exchangeable image carrier, in particular a storage film or an X-ray film, and that the measuring device comprises a marking object ( 102 ) located between the X-ray source ( 28 ) and the image carrier, wherein the equalization device determines the position of the image of the marking object ( 102 ) on the image carrier, the position of the image carrier relative to the X-ray source ( 32 ) can be determined.

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