WO2010118895A1 - Holding device, bite element and system for intraoral radiography - Google Patents

Abstract

The invention relates to a bite element, a holding device, a method, a computer program product and a system for creating and/or processing intraoral shadow images, in particular X-ray images. To this end, a holding device comprises a device base which is designed to define a determined or determinable position of a projection surface, in particular a planar projection surface, of a radiation detector relative to a radiation source; and a bite element which is located at the device base so as to be rotated about a base rotation axis, said element comprising a shadow reference element such that the shadow reference element does not have a continuous rotation symmetry with respect to an axis parallel to the base rotation axis. This results in a distortion of the shadow of the shadow reference element in a shadow image, depending on an image angle during imaging. This also allows for taking potential distortions of the region to be examined (such as tooth) on the shadow image due to an inclined image angle to be taken into account solely based upon the evaluation of the shadow image, without requiring an explicit measurement of the image angle during imaging.

Description

 Vooldvoπϊchtung, Aufbisselement and system for intraoral radiography "

description

The invention relates to the improvement of intraoral silhouette recordings or radiography, in particular X-ray recordings. In particular, the invention provides a holding device, a bite element for such a holding device and a system for producing intraoral silhouette recordings and a method for processing data of intraoral silhouette recordings.

A shadow image is understood to be any type of transilluminating projection image, in particular X-ray images, which takes place on the basis of radiation which at least partially penetrates a tissue, in particular organic tissue, depending on its composition and / or thickness and its projection onto a projection surface or a projection surface Projection screen a silhouette of the at least partially illuminated or irradiated tissue results. In particular, it can be used to examine teeth or a single area of a patient's teeth or jaw. For this purpose, in particular X-ray images are known. In order to achieve good visibility of the tissue to be examined on the shadow image, it is advantageous to have to irradiate as little additional tissue between a radiation source and the tissue to be examined or between the tissue to be examined and the projection screen. This avoids unwanted shadow overlay. In particular, in the examination of teeth and / or jaw areas, it is therefore advantageous to place the projection screen, for example in the form of a x-ray-sensitive film in the oral cavity of the patient, while the radiation source, in particular an x-ray tube, sends radiation from outside the oral cavity onto the projection screen. In order to improve a simple and flexible arrangement of the projection screen within the oral cavity, DE 195 81 556 T1 proposes to arrange a film holder and an adjusting rod each independently pivotable on a bite and provide angle scales, where the respective swing angle can be read. Further pivotable holders are known from US 4 633 493 and US 5 119 410. In each case, an adjusting rod for adjusting an X-ray source is connected to a film holder in such a way that a vertical projection onto an X-ray film is always ensured, while the entire beam direction can be tilted relative to a tooth to be examined. Thus, the film holder can be aligned together with the beam direction depending on the anatomy of the oral cavity or the teeth.

The object of the present invention is to simplify the creation and evaluation of intraoral shadow images. This object is achieved by a holding device, a bite element, a method, a computer program product and a system having the features specified in claims 1, 9, 17, 24 and 25, respectively. Preferred embodiments are subject of the dependent subclaims.

Thus, the invention provides a holding device for the production of intraoral shadow images, in particular X-ray images, which comprises: a device base, in particular a connecting frame, which is designed, a specific or determinable position of a particular planar projection surface of a radiation detector relative to a radiation source set; and a bite member rotatably mounted on the device base about a base rotational axis and including a shadow reference member such that the shadow reference member does not have continuous rotational symmetry with respect to an axis parallel to the base rotational axis. Thus, the device base ensures a defined projection geometry. In particular, the beam path of the shadow image (eg, X-ray) is accurately determined by determining the relative position, particularly the relative distance and the relative orientation, between the radiation source and the projection surface of the radiation detector by means of the device base. This allows a reliable inference to the intermediate material or tissue whose shadow is projected onto the projection surface, or at least to its cross section under the respective imaging angle. The biting element makes it possible to achieve at least partial fixation of the holding device relative to a tooth or jaw of a patient. For this purpose, the bite element is fixed in particular between antagonistic teeth of the patient. The patient may bite the bite element during the creation of the intraoral shadow image. For this purpose, it preferably has a first (or upper) and a second (or lower) bite surface. As a result of the rotatable arrangement of the bite element on the device base, the device base is also rotatable about the base rotational axis, even if the bite element is fixed relative to a tooth, in particular relative to a tooth axis of a tooth to be examined, while the relative positioning of the radiation source to the projection surface remains unchanged. This rotatability or tiltability of the device base allows a simple and at the same time reliable alignment and adaptation of the beam path or the radiation detector and the radiation source to the individual anatomical conditions of the respective patient. In particular, the position of the radiation detector in the oral cavity of the patient can thus be adapted to the respective shape of the oral cavity, in particular to the palatal curvature, without changing the geometry of the beam path. As a result, the creation of the shadow image recording for a patient is more pleasant or bearable, since, for example, a mechanical pressure can be reduced or avoided especially on the patient's palate. On the other hand, a reliable shadow recording is achieved by the specified radiation geometry. The rotation of the device base around the bite element fixed relative to the tooth or to the tooth axis merely changes the imaging angle, ie, for example, the alignment of the tooth axis of a tooth to be examined relative to the direction of the rays. The distance and the orientation of the beam source and thus the beam geometry relative to the projection surface remains unchanged and thus accurately determined or determinable. The change in the imaging or viewing angle caused by rotation or tilt leads to a correspondingly altered shadow image. However, not only the shadow image of the area to be examined (eg tooth and / or jaw section), but also the shadow image of the shadow reference element encompassed by the bite element due to its lack of continuous rotational symmetry of the imaging or viewing angle, ie the twisting or tilting or Swing angle of the bite element relative to the device base from. As a continuous rotational symmetry is understood to mean a symmetry with respect to a rotation at an arbitrary angle. This symmetry is also called cylindric symmetry. In contrast, a discrete rotational symmetry of the shadow reference element is generally permitted. For example, the shadow reference element may have a symmetry with respect to a rotation about an axis parallel to the base axis of rotation by 180 °.

The device base makes it possible to ensure a defined projection geometry such that the bite element is positioned in the beam path of the shadow image such that the shadow image of the shadow reference element lies completely within the projection area in the entire utilized or usable range of tilt angles and in particular the area to be examined, in particular Tooth or jaw, not completely covered. Preferably, the shadow reference element is configured in size and position in relation to the device base such that the shadow image of the shadow reference element essentially comes to rest in an edge region of the projection surface. As a result, in particular the central surface area of the projection surface can be used for an object to be examined. In particular, the shadow reference element is in its size designed such that its silhouette is visually well resolved. In particular, when using a digital radiation detector, the shadow image is thus at least a multiple of a pixel size.

In any case, due to the absence of a continuous rotational symmetry, the shadow-generating cross section of the shadow reference element at least partially depends on the irradiation or imaging angle. Thus, the reference shadow projected onto the projection surface, in particular its shape and / or size, of the shadow reference element of known form and / or size permits a conclusion about the imaging angle. Thus, even after the recording has been taken, the exact geometry, including the recording angle, can be deduced on account of the reference shadow of the shadow reference element contained in the shadow recording. This can also take into account possible distortions of the region to be examined (for example tooth) on the shadow image due to an oblique acceptance angle in the evaluation of the shadow image. This improves the accuracy and validity of such silhouette images, especially X-rays. It also simplifies the creation of these images, as a separate measurement of the angle used is not required and the angle can be freely adapted to the individual anatomical conditions. The possibility of adaptation to the individual anatomical conditions also increases the comfort for the respective patient.

Distortion is understood to be, in particular, the ratio of the maximum to the minimum axial magnification in the various directions when imaging an object that is tilted, in particular, the ratio between the projected size and the true size of an object in a direction transverse to the beam direction as axial magnification , If an object to be imaged, such as a tooth, is tilted about an axis deviating from the beam direction, the imaged size, ie the axial magnification, is reduced relative to the true size, in particular in the direction perpendicular to the tilting axis. This axial magnification is in particular the minimum axial magnification. The axial magnification perpendicular to it is preferably not affected by the tilting substantially. The ratio of these two axial magnifications thus represents in particular the distortion. The distortion thus depends in particular on the tilt angle.

Preferably, the device base comprises a detector holder, in particular a clamping holder and / or plug holder, for holding a radiation detector, wherein the detector holder is arranged on a first base portion of the device base such that the position of the projection surface of a radiation detector relative to the base rotational axis is changeable or adjustable. Preferably, the first base portion is adjustable in length. In another preferred aspect, the device base includes a detector rotation axis about which the detector holder is pivotable relative to the first base portion. Preferably, the detector rotation axis is arranged parallel to the base rotation axis. The detector holder is preferably designed for a radiation-sensitive film (for example an X-ray-sensitive film) and / or an electronic, spatially resolving radiation sensor, in particular

Semiconductor sensor, hold. In particular, the length and / or Winkelversteilbarkeit a particularly flexible adaptation to individual anatomical conditions of each patient can be achieved.

Preferably, the first base portion comprises a detector pitch scale for reading a variable linear position of the detector holder relative to the base rotational axis; and / or a detector angle scale for reading a variable angle of the detector holder relative to the first base portion. Alternatively or additionally, the first base portion preferably comprises a detector pitch sensor for automatically determining a variable linear position of the detector holder relative to the base rotational axis; and / or a detector angle sensor for automatically determining a variable angle of the detector holder relative to the first base portion. In this way, the exact projection geometry in the respective individual case can be detected simply and in particular even automatically, which is the subsequent or later evaluation or interpretation of a created shadow image simplifies and their expressiveness or usability in terms of absolute sizes improved.

Preferably, the device base comprises a positioning element, in particular a positioning ring, for applying and / or fixing a radiation source, wherein the positioning element is arranged on a second base portion of the device base such that the position of the radiation source is changeable or adjustable relative to the base rotational axis. Preferably, the second base portion is adjustable in length. In another preferred aspect, the device base includes a source rotation axis about which the positioning member is rotatable relative to the second base portion. Preferably, the source rotation axis is arranged parallel to the base rotation axis. This allows a further, flexible adaptation of the radiation geometry to the individual circumstances. Preferably, the positioning element comprises a positioning ring, which is designed for applying and adjusting an X-ray tube.

Preferably, the second base portion includes a source pitch scale for reading a variable linear position of the positioning member relative to the base rotational axis; and / or a source angle scale for reading a variable or adjustable angle of the positioning relative to the second base portion. Alternatively or additionally, the second base portion preferably comprises a source pitch sensor for automatically determining a variable linear position of the positioning member relative to the base rotational axis; and / or a source angle sensor for automatically determining a variable angle of the positioning member relative to the second base portion. In this way, the exact projection geometry in the respective individual case can be detected simply and in particular even automatically, which simplifies the subsequent or later evaluation or interpretation of a created shadow image recording and improves its informative value or usability with regard to absolute variables. In a further aspect, the present invention provides a bite element for a holding device for the production of intraoral shadow recordings, in particular X-ray recordings, in particular for a holding device according to the invention or preferred embodiment thereof, which comprises a bite block with a first or primary bite surface and a preferably first substantially parallel second and secondary bite surfaces, respectively, wherein the bite block is rotatably mountable about a base rotational axis of the bite block to a device base of the holder; a shadow reference element which is so firmly connected to the bite block or removably or non-detachably firmly connectable that it has no continuous rotational symmetry with respect to an axis parallel to the base axis of rotation.

This makes it possible to achieve the above-mentioned improvement in the generation and evaluation of intraoral shadow images, since when creating shadow images together with a region of a tooth or jaw of a patient to be examined, any distortion of the shadow of the shadow reference element from an irradiation angle relative to the bite element depends. By comparing the known dimensions and / or arrangement of the shadow reference element in the bite element with its generated reference shadows, it is possible to draw conclusions about the irradiation angle without having to measure it directly during the creation of the image.

Preferably, the holding device according to the invention comprises a bite element according to the present invention or according to one of the preferred embodiments of a bite element described below. In particular, the shadow reference element comprises material other than the bite block. Preferably, the shadow reference element comprises material that is not included in the bite block. Particularly preferably, the shadow reference element comprises material of another, in particular higher, density and / or a higher atomic number than the Aufbissblock. In a preferred embodiment, the shadow reference element comprises metal, in particular iron and / or tungsten and / or gold and / or lead. Preferably, the shadow reference element comprises metal with an atomic number of at least 26, more preferably at least 40, even more preferably at least 74.

Preferably, the shadow reference element has no higher rotational symmetry than a symmetry with respect to a rotation about an axis parallel to the base axis of rotation about 180 °. More preferably, the shadow reference element does not exhibit rotational symmetry about an axis parallel to the base axis of rotation (other than identity, i.e., rotating through 0 ° or 360 °). This allows an analysis and an inference to a particularly large angular range. The holding device is thus very efficient even for very large tilt angle.

Preferably, the shadow reference element comprises a wire section having a length in the range of at least about 0.5 mm, preferably at least about 1 mm, particularly preferably at least about 2 mm. Preferably, the length of the wire section is at most about 15 mm, more preferably at most about 10 mm, even more preferably at not more than about 6 mm. Preferably, the length ranges from about 0.5 mm to about 15 mm, preferably from about 1 mm to about 10 mm, more preferably from about 2 mm to about 6 mm. In another aspect, a thickness or diameter of the wire section is in the range of at least about 0.1 mm, preferably at least about 0.2 mm, more preferably at least about 0.5 mm. Preferably, the thickness or diameter of the wire section is at most about 2 mm, more preferably not more than about 1 mm. Preferably, the thickness or diameter ranges from about 0.1 mm to about 2 mm, preferably from about 0.2 mm to about 1 mm, more preferably from about 0.5 mm to about 1 mm , In a preferred embodiment, the shadow reference element is arranged completely inside the bite block, ie in this case the shadow reference element is completely surrounded by material of the bite block. This ensures good protection of the shadow reference element against mechanical and / or chemical influences during use or during cleaning. This is particularly desirable for fine feature sizes of the shadow reference element. In addition, this encapsulated integration of the shadow reference element is particularly desirable when using non-noble metals. In this way, for example, when using lead for the shadow reference element direct contact with the patient, especially in the mouth can be prevented.

In another preferred embodiment, the shadow reference element is at least partially disposed on or on a surface or outer surface of the bite block. Such a construction, which in particular when using inert materials, such as. Precious metals, is to be considered, is particularly in view of the ease of manufacture and thereby achievable accurate positioning of the shadow reference element preferred.

Preferably, the shadow reference element is arranged in a plane parallel to the base axis of rotation. Alternatively or additionally, the shadow reference element lies in a plane parallel to the base axis of rotation, which plane is perpendicular to the first and / or second bite surface. In a further preferred embodiment, the shadow reference element lies in a plane parallel to the base axis of rotation, which plane is parallel to the first and / or second adjacent surface and / or extends through the base axis of rotation.

Preferably, the shadow reference element comprises a first longitudinal section in the form of a rectilinear wire element having a determinable length (longitudinal section length) lying in a plane perpendicular to the base axis of rotation. Preferably, the longitudinal portion is arranged perpendicular to the first (primary) and / or second (secondary) Aufbissfläche the Aufbissblocks. In another preferred embodiment, the longitudinal portion is arranged parallel to the first and / or second Aufbissfläche the Aufbissblocks. This can be achieved in practical application particularly good resolutions for the desired distortion corrections.

The shadow reference element preferably comprises a first transversal section in the form of a rectilinear wire element with a specific or determinable length (first transversal section length) which lies on a straight line parallel to the base rotational axis. This first transverse section thus has a continuous rotational symmetry about an axis parallel to the base rotational axis. It thus represents only a part of the shadow reference element. The reference shadow thus produced, in particular its length (first transversal reference length) or the ratio of the first transversal reference length to the first transversal section length, is a measure of enlargement of the shadow image recording. This allows for example already from the shadow image conclusions on the beam geometry, in particular to ratios of the distances of the shadow reference element, in particular the first transverse section, the radiation source and the projection screen, without having to measure all set positions or distances of the fixture directly. This simplifies the process of creating shadow images and improves their evaluation.

Preferably, the shadow reference element comprises a second transverse section in the form of a rectilinear wire element having a certain or determinable length (second transverse section length) lying in a straight line parallel to the base rotational axis, on which the first transverse section does not lie. Preferably, the second transversal section length coincides with the first transversal section length. Like the first transversal reference length, the length of the reference shadow of the second transversal section (second transversal reference length) also allows conclusions to be drawn about the ratios of the distances of the second transversal section to the radiation source and to the Projection screen too. From the known relative position of the first and second transversal sections and from the transversal reference lengths it is thus possible to even draw conclusions about the absolute distances. From the relative position of the reference shadows to each other, ie from the distance of the reference shadows conclusions can be drawn on the tilt angle. This makes it possible to evaluate the shadow image in a particularly efficient manner without having to measure additional settings on a holding device during the production of the image.

In a further aspect, the invention provides a method, in particular computer-implemented, for processing intraoral shadow image data, which comprises:

Providing primary image data of an intraoral shadow image;

Providing shadow reference data defining dimensions of a shadow reference element;

Detecting a shape and / or size of a reference shadow of the shadow reference element defined in the primary image data; and

Determining scaling data that defines a scaling of the shape and / or size of the reference shadow relative to the dimensions of the shadow reference element defined in the shadow reference data.

By means of this data processing method according to the invention, the above-described improvement in the generation and evaluation of intraoral shadow recordings can be achieved, since the determination of scaling data as a function of acquired data of a shadow of a shadow reference element efficiently and accurately takes into account the distortion of the shadow image due to tilting the beam path is made possible without such a tilt during the creation of the recording must be measured directly and logged. Preferably, the determination of scaling data comprises determining a rotation angle, in particular a tilt angle of a device base relative to a bite element about a base rotation axis. Preferably, a distortion of the shadow image is determined therefrom. Preferably, determining scaling data comprises determining a magnification. In particular, the method preferably comprises determining a real length of a tooth from the provided primary image data and the scaling data, in particular the tilt angle.

Preferably, the method includes determining secondary image data by scaling the primary image data using the scaling data. More preferably, the method includes visually displaying a secondary shadow image in response to the secondary image data. In this case, the secondary shadow image is preferably output on a screen and / or a printer. In this way, for a medical evaluation, possible distortion of a primary shadow image due to an oblique radiation incidence, for example, on a tooth or jaw area to be examined, is efficiently eliminated.

Preferably, the provision of primary image data comprises using a holding device according to the present invention or a preferred embodiment thereof, in particular with a bite element according to the present invention or a preferred embodiment thereof for creating a primary intraoral shadow image, in particular X-ray. In another aspect, preferably, such determined primary image data is provided as a digital data set for processing.

Preferably, detecting the primary intraoral shadow image comprises detecting an adjustable linear position of the detector holder and / or the projection surface relative to the base rotational axis; and or detecting an adjustable angle of the detector holder and / or the projection surface relative to the first base portion; and / or detecting an adjustable linear position of the positioning member relative to the base rotational axis; and / or detecting an adjustable angle of the positioning member relative to the second base portion.

Preferably, the detection of the respective position or of the respective angle takes place by detecting a manual input, in particular via a graphical user interface and / or by, in particular, automatically acquiring data from a detector or source distance or angle sensor, which is preferably temporarily stored for further processing and provided in this way.

In a further aspect, the invention provides a computer program product, in particular in the form of a machine-readable medium, configured as a signal and / or as a data stream, comprising program code loaded and executed in a computer system, this computer system for carrying out a method according to the present invention or a preferred embodiment.

In a further aspect, the invention provides a system for generating and / or processing intraoral shadow images, in particular X-ray images, which comprises: a shadow image acquisition device for acquiring primary image data of an intraoral shadow image projected onto a projection surface; a reference shadow detection module for detecting a shape and / or size of a reference shadow of a shadow reference element defined in the primary image data; and a reference shadow analysis module for determining scaling data which is a scaling of the detected shape and / or size of the Define or describe reference shadow relative to dimensions of the shadow reference element.

Preferably, the system also includes a shadow scaling module configured to determine secondary image data by scaling the primary image data using the scaling data. Most preferably, the system also includes an image output unit configured to output a secondary shadow based on the secondary image data.

For a method according to the invention, a holding device and / or a bite element and / or a system according to the invention or a preferred embodiment thereof is preferably used.

The invention will now be described by way of example with reference to the accompanying drawings of preferred embodiments. Showing:

1A-C are schematic views of a holding device according to a first preferred embodiment of the present invention from a side view (FIG. 1A) of a plan view (FIG. 1B) and a front view (FIG. 1C);

Fig. 2 is a schematic view of the arrangement of radiation source and

Projection screen when taking a shadow image in the area of the upper jaw of a patient;

FIG. 3 shows a schematic representation of a simple projection geometry for illustrating the generation or evaluation of shadow images according to the present invention; FIG.

FIGS. 4A-D are perspective, schematic representations of bite elements according to preferred embodiments of the present invention; Fig. 5 is a photo of a holding device according to another preferred

Embodiment of the present invention; and

Fig. 6 shows an exemplary system for processing intraoral data

Silhouette images especially for implementing a method according to a preferred embodiment of the present invention.

1A to 1C show schematic views of a holding device 10 according to a first preferred embodiment of the present invention viewed from different directions, wherein in each figure the relative viewing directions of the respective other figures are indicated by corresponding letters "A" (corresponding to the viewing direction in Fig. 1A). 1B) and "C" (corresponding to the viewing direction in Fig. 1C) are marked, in particular Fig. 1A is a side view, Fig. 1B is a plan view and Fig. 1 C is a front view in the radiation direction. In this preferred embodiment, the fixture 10 includes a fixture base having a first base portion 12 and a second base portion 14. Provided on the fixture base is a base shaft 16 over which a bite member 18 about a base pivot axis 20 rotatably or pivotally angeord to the device base net or attached. For this purpose, the device base in particular has a Aufbissmontageelement 22, in which the base shaft 16 is fixed or rotatably supported about the base axis of rotation 20.

The first base section 12 connects the bite mounting element 22 to a detector holder 24, which is designed, for example, as a clamp holder or plug holder for holding a radiation detector with a projection surface 26. In particular, a radiation-sensitive film and / or a digital radiation detector could be used as the radiation detector. Here, the first base portion 12 is designed to hold the projection surface 26 in a specific or determinable, in particular adjustable position relative to the base axis of rotation 20. Preferably, the first base portion 12 is in a longitudinal direction L1 changeable or adjustable. Particularly preferably, the first base portion 12 has a measuring scale, by means of which the set in the L1 direction position can be read. In another preferred embodiment, the first base section has a detector distance sensor for, in particular, automatically determining the position set in the L1 direction.

The second base portion 14 connects the Aufbissmontageelement 22 with a positioning, which is formed in the preferred embodiment shown here in the form of a positioning ring 28 for applying and / or fixing a radiation source, in particular an X-ray tube or an X-ray tube. In particular, the X-ray tube can be attached to the positioning ring such that a central ray 30 strikes the radiation emitted by the X-ray tube as a radiation source, in particular perpendicular to the projection surface 26. For this purpose, the positioning ring 28 preferably defines a positioning plane (perpendicular to the central beam 30) and a substantially circular beam passage opening such that the central beam passes through the center of the substantially circular beam passage opening. "Substantially circular" in this context means, in particular, that the beam passage opening can be inscribed with a circle lying in the positioning plane, which is at least somewhat 0.7 times, preferably at least approximately 0.8 times, particularly preferably at least about 0.9 times, more preferably at least about 0.95 times, most preferably at least about 0.98 times the cross section of the beam passage opening contains or covers. In a further preferred embodiment, the beam passage opening is essentially rectangular.

The second base section 14 is in particular designed to hold the positioning element 28 in a specific or determinable, in particular adjustable position relative to the base rotational axis 20. Preferably, the second base portion 14 in a longitudinal direction L2, which preferably extends parallel to the longitudinal direction L1, changeable or adjustable. Particularly preferably, the second base section 14 has a measuring scale, by means of which the set in the L2 direction position can be read. In another In a preferred embodiment, the second base section has a source distance sensor for, in particular, automatically determining the position set in the L2 direction. Thus, the first base portion 12 and the second base portion 14 together ensure relative positioning of the radiation detector and the radiation source to each other. In the embodiment shown here, in particular, the projection surface 26 and the positioning plane defined by the positioning element are parallel to each other.

In the embodiment illustrated in FIG. 1, the biting element 18 has a first or primary bite surface 32 and a second or secondary bite surface 34 parallel thereto, which is arranged opposite the first bite surface 32 in such a way that the bite element is between antagonistic teeth a patient can be fixed by the patient with these antagonistic teeth bites on the first 32 and second Aufbissfläche 34. The patient preferably bites with a tooth to be examined on the first or primary bite surface 32 and with a corresponding antagonistic tooth on the second or secondary bite surface 34. In this case, the tooth axis of the tooth to be examined is preferably substantially perpendicular to the first or primary Aufbissfläche 32. Preferably, at or on the first Aufbissfläche 32 Fixiernoppen or depressions are provided to prevent slipping of the bite element 18. Preferably, the first 32 and second bite surfaces 34 have a mutual spacing in the range of at least 3 mm, preferably not less than about 5 mm, more preferably not less than about 1 cm. In a further aspect, the biting surfaces preferably have a mutual spacing in the range of not more than 2.5 cm, more preferably not more than about 2 cm, even more preferably not more than about 1.5 cm, and most preferably not more than about 1 cm up. In a preferred embodiment, the mutual distance of the Aufbissflächen is changeable or adjustable. This makes it possible to achieve a particularly precise adaptation to the respective patient or the respectively to be examined tooth or jaw area. In the preferred embodiment shown in Fig. 1, the bite element 18 at a proximal or inner Edge of the first Aufbissfläche on a positioning strip 36 which projects beyond the first Aufbissfläche or protruding and facilitates a reproducible positioning of the bite element relative to a tooth to be examined.

In the bite block of Aufbisselements 18 a Basiswellenausnehmung is provided in which the base shaft 16 is rotatably supported or fixed such that the bite element about the base axis of rotation 20 relative to the device base and in particular relative to the Aufbissmontageelement 22 is rotatable or pivotable. Preferably, the first 32 and / or the second Aufbissfläche 34 is parallel to the base axis of rotation 20th

In addition, a shadow reference element 38 is embedded in the bite block of the bite element 18, which is formed in the preferred embodiment shown in FIG. 1 in the form of a straight wire element which runs perpendicular to the first bite surface 32 and lies in a common plane with the base axis of rotation 20. In particular, this wire element between the base rotation axis 20 and the first Aufbissfläche 32 is arranged. Thus, it is in the vicinity of the tooth to be examined and is also imaged on the projection surface 26 when creating a shadow image of the tooth.

FIG. 2 shows a schematic view of the arrangement of an X-ray tube 40 as a radiation source and a projection screen or a projection surface 26 during the production of a shadow image in the area of the upper jaw of a patient. In this case, the X-ray tube 40 is arranged directly or indirectly on the positioning ring 28 and / or attached to the positioning ring 28. In particular, the X-ray tube 40 can be arranged on the positioning ring 28 such that a reproducible beam direction and a reproducible focus distance relative to the holding device are made possible. In this case, a bite element 18 with a first bite surface 32 is arranged on a tooth 42 of a patient to be examined. In particular, the patient with the tooth 42 to be examined bites on the first bite surface 32 of the bite element 18. As a result, the bite element 18 essentially becomes the tooth 42 aligned so that a perpendicular 44 extends to the first Aufbissfläche substantially parallel to a tooth axis of the tooth 42 to be examined.

To be able to arrange the projection surface 26 in the oral cavity of the patient in such a way that a shadow image of the tooth to be examined can be created, the device base together with the projection surface 26 must be tilted by an angle γ due to the palatal curvature 46. Due to the inherently rigid arrangement of the projection surface 26 relative to the X-ray tube 40, the beam geometry remains unchanged. In particular, the X-rays emanate substantially point-like from a radiation diaphragm not explicitly shown in FIG. 2 and impinge on the projection surface 26 after the at least partial penetration of the tooth 42 and the surrounding tissue and jaw region, which propagates from this point-shaped radiation source Central ray 30 in turn strikes the projection surface 26 perpendicularly.

However, the oblique incidence of the radiation relative to the tooth axis leads to a distorted shadow image of the tooth 42 on the projection surface 26. In particular, the length of the tooth 42 in the direction of the tooth axis in the shadow image recording is shortened. According to the invention, however, the bite element comprises a shadow reference element 38, which likewise generates a shadow on the projection surface. For this purpose, the shadow reference element 38 preferably comprises material with a high atomic number, in particular metal. As a result, a high x-ray opacity and thus a clear or sharp reference shadow 48 are preferably achieved. Due to a lack of continuous rotational symmetry of the shadow reference element 38 for rotations about axes parallel to a base axis of rotation, the shadow-generating cross-section of the shadow reference element 38 depends on the tilt angle γ. Due to the known dimensioning and arrangement of the shadow reference element 38 within the bite element 18, the analysis of the shadow reference element 38 on the projection surface 26 can thus be generated Reference shadow 48, so solely on the basis of the generated shadow image without direct measurement of the tilt during the creation of the shadow image on the tilt angle γ infer.

FIG. 3 illustrates aspects of a method for processing intraoral shadow image data based on a simple projection geometry. In general, the image, in particular the X-ray image, follows the principle of projective transformation, in which an object point P of the three-dimensional space with the coordinates [χ _P , y _P , z _P ) to a pixel P 'in the two-dimensional space with the coordinates [x _/ ..,; »] is displayed P → F. If the designations from FIG. 3 are taken as a basis, ie the distance between the projection surface or plane and the radiation source, in particular the focus or aperture of the radiation source, is d + d '= z, then the image is obtained (in homogeneous coordinates) :

The coordinates [χ _P , y _P , z _P ] can be calculated from the known structure of the holding system. The two-dimensional representation of FIG. 3 illustrates a simple example in which the focal point or the substantially punctiform radiation source lies at F (θ, O, z). The shadow reference element 38 has a length a. The distance of the substantially point-shaped radiation source from the projection surface is z = d + d '. The distance of an end point of the rod-shaped or wire-shaped shadow reference element from the radiation diaphragm lying on the central beam 30 is d, while the distance of this end point from the projection surface d 'is. The imaged length of the shadow reference element, ie the length of the reference shadow 48, is ά. The tilt angle γ results as follows: a 'b_ da' b = (2) zd

In addition:

a = 90 ° - φ (3) and

9? = arctane -. (4) z

Since the direction of tilting of the image capture plane is predetermined by the palatal curvature, it can preferably be assumed that a> b. Therefore, β is clearly specified by

, _o bsina _o . bsina ._. sin / 7 = => /? = arcsm. (5) aa

By substituting the results of equations (3) and (5), the sought angle γ is given by: γ = nQ ° - (a + β). (6)

In this way, a posteriori of image information can be used to calculate a tilt angle that occurred when creating a shadow image. The shadow reference element provided on the bite element serves this purpose. Viewed in a geometrically simplified manner, teeth are cylindrical bodies whose longitudinal axis, viewed also in a simplified manner, runs approximately parallel to the axis of inertia of the pulp cavity. Distortions in the direction of this longitudinal axis, which can be determined and preferably corrected with the aid of the present invention, are of particular interest in endodontics and also many surgical problems.

The actual object length L (analogous to the distance a in FIG. 3) of an object to be examined becomes from the length L imaged on the image plane (analogously to the distance ά in FIG. 3) and the angle γ determined from equation (6) analogously to the calculations from the equations (2) to (6). Since the angles are in particular identical, one calculates the length L _b projected onto a parallel to the image capture plane shifted in the direction of focus

(analogous to the distance b in Fig. 3). This is preferably determined analogously to equation (2):

d £

_Lb = - (7) z

The searched object length L can finally be determined from the angles known from equations (3) and (5) and the result of equation (7)

L =! * S≡in p £ (8)

Investigations have been made on an exemplary, partially handcrafted embodiment of a preferred fixture on an X-ray dummy. This handcrafted embodiment has appropriate tolerances (about ± 1, 5mm and ± 3 °). The shadow reference element (steel wire, diameter about 0.7 mm, length: about 4 mm) was measured manually on the X-ray images. The resulting deviations between the actual length of the teeth (determined by measuring with a vernier caliper) and the calculated length are given in Tab. Seven measurements showed a mean absolute error of 0.35 mm (± 0.18 mm).

Steel wire 7 actual length calculated absolute relative length error error

13 ° 15.0 mm 15.66 mm 0.66 mm 4.40%

26 ° 15.0 mm 15.47 mm 0.47 mm 3.13%

23 ° 15.0 mm 15.15 mm 0.15 mm 1.00%

16 ° 15.0 mm 14.61 mm 0.39 mm 2.60%

17 ° 15.0 mm 14.84 mm 0.16 mm 1, 07%

6 ° 15.0 mm 15.38 mm 0.38 mm 2.53%

3 ° 15.0 mm 15.38 mm 0.27 mm 1, 80%

Mean value 15.00 mm 15.20 mm 0.35 mm 2.36%

SD 0.037 0.18 mm 1, 20%

Table 1: Study results using the manually made prototype.

The preliminary test data shows that despite relatively large tilt angles present, i. Angle between the tooth axis and projection surface and a large manufacturing error of the handmade prototype already result in relatively accurate readings. Mainly, the inaccuracy can be attributed to the use of a shadow reference element which can not be precisely measured and placed, which was also made of steel and not of a denser material (eg lead). A photograph of such a holding device is shown in FIG. The individual corresponding components are provided with the reference numerals already used in connection with other preferred embodiments.

FIGS. 4A to 4D show schematic representations of further preferred embodiments of bite elements 18 with different configurations of the shadow reference element. Thus, Fig. 4A shows a shadow reference element similar to the bite element already shown in the embodiment of Fig. 1. In this embodiment, the Shadow reference element in particular a longitudinal portion 38a in the form of a straight wire element, which is perpendicular to the base axis of rotation. Other analogous components of these bite elements 18 are provided with the same reference numerals as in the previously described embodiments.

4B shows another preferred embodiment of a bite element 18 in which the shadow reference element comprises, in addition to a longitudinal section 38a, a first transverse section 38b which is in the form of a rectilinear wire element arranged parallel to the base axis of rotation. In the embodiment shown in FIG. 4C, the shadow reference element comprises a first transversal section 38b and a second transversal section 38c, the reference shadows of which have a mutual distance as a function of a tilt angle. In a particularly preferred embodiment, the shadow reference element could already have a scale-formed section 38d, the shadow of which is shifted in dependence on a tilt angle relative to the reference shadow of a pointer-shaped or acting section 38c. Such a configuration is shown schematically in Fig. 4D. In this way, a measure of the tilt angle or the tilt angle itself can be determined directly from the shadow image recording in a simple manner.

Referring to Fig. 6, an exemplary system for implementing the invention, particularly a computer-implemented method for processing intraoral shadow image data, will be described. An exemplary system includes a universal computing device in the form of a conventional computing environment 120, such as a personal computer (PC) 120, having a processor unit 122, system memory 124, and system bus 126 which includes a variety of system components, including system memory 124 and the processor unit 122 connects. The processing unit 122 may perform arithmetic, logic and / or control operations by accessing the system memory 124. The system memory 124 may store information and / or instructions for use in combination with the processor unit 122. The system memory 124 may include volatile and non-volatile memory, such as random access memory (RAM) 128 and read-only memory (ROM) 130. A basic input-output system (BIOS) containing the basic routines that help to transfer information between the elements within the PC 120, such as during start-up, may be stored in the ROM 130. The system bus 126 may be one of many bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus employing a particular bus architecture from a variety of bus architectures.

The PC 120 may further include a hard disk drive 132 for reading or writing a hard disk (not shown) and an external disk drive 134 for reading or writing a removable disk 136 or a removable disk. The removable disk may be a magnetic disk for a magnetic disk drive or an optical disk such as a floppy disk. a CD-ROM for an optical disk drive. The hard disk drive 132 and the external disk drive 134 are each connected to the system bus 126 via a hard disk drive interface 138 and an external disk drive interface 140. The drives and associated computer readable media provide nonvolatile storage of computer readable instructions, data structures, program modules and other data to the PC 120. The data structures may include the relevant data for implementing a method as described above. Although the exemplary environment uses a hard disk (not shown) and an external disk 142, it will be apparent to one of ordinary skill in the art that other types of computer-readable media that can store computer-accessible data may be used in the exemplary work environment, such as e.g. magnetic cassettes, flash memory cards, digital video disks, random access memory, read-only memory, etc.

A plurality of program modules, in particular an operating system (not shown) one or more application programs 144, or program modules (not shown) and program data 146 may be stored on the hard disk, the external disk 142, the ROM 130 or the RAM 128. The application programs may include at least a portion of the functionality as shown in FIG.

A user may enter commands and information into the PC 120, as described above, using input devices, such as a mouse. a keyboard or keyboard 148 and a computer mouse or trackball 150. Other input devices (not shown) may include a microphone and / or other sensors, a joystick, a game pad, a scanner, or the like. These or other input devices may be connected to the processor unit 122 via a serial interface 152 coupled to the system 126, or may be interfaced with other interfaces, such as those shown in FIG. a parallel interface 154, a game port or a universal serial bus (USB). Furthermore, information may be printed with a printer 156. The printer 156 and other parallel input / output devices may be connected to the processor unit 122 through the parallel interface 154. A monitor 158 or other type of display device (s) is / are connected to the system bus 126 via an interface, such as a computer. a video input / output 160 connected. In addition to the monitor, the computing environment 120 may include other peripheral output devices (not shown), such as those shown in FIG. Speaker or acoustic outputs include.

The computing environment 120 may communicate with other electronic devices, such as a computer, a cordless phone, a cordless phone, a personal digital assistant (PDA), a television, or the like. To communicate, computing environment 120 may operate in a networked environment using connections to one or more electronic devices. FIG. 10 illustrates the computing environment networked to a remote computer 162. The remote computer 162 may be another computing environment, such as a server, a router, a network PC, an equivalent peer. Device or other common network nodes, and may include many or all of the elements described above with respect to computing environment 120. The logical connections as illustrated in Figure 10 include a local area network (LAN) 164 and a wide-area network (WAN) 166. Such networking environments are commonplace in offices, corporate-wide computer networks, intranets, and the Internet.

When a computing environment 120 is used in a LAN network environment, the computing environment 120 may be connected to the LAN 164 through a network input / output 168. When the computing environment 120 is used in a WAN networking environment, the computing environment 120 may include a modem 170 or other means of establishing communication over the WAN 166. The modem 170, which may be internal and external to the computing environment 120, is connected to the system bus 126 via the serial interface 152. In the network environment, program modules that are relative to the computing environment 120, or portions thereof, may be stored in a remote storage device that is accessible to or from a remote computer 162. Furthermore, other data relevant to the method or system described above may be accessible on or from the remote computer 162.

In particular, it is achieved by the present invention that, by measuring the shadow image of the shadow reference element, the projection geometry effective for the exposure time with respect to the direction of passage of the radiation through the object, ie the tilt angle, together with the associated distances (source object and object projection plane) can be estimated can. This is achieved in particular by the design of the holding system or the holding device with a rotatable bite element and the recordings on the geometries of the imaged objects (teeth, implants, etc.) in that the shadow reference element is or is aligned in the holding system or the holding device. and its shape is chosen accordingly) that in Direction of interest object axis (s) information is generated. The latter then serve to correct the object image, ie the generation of the secondary shadow image.

LIST OF REFERENCE NUMBERS

10 holding device

12 first base section

14 second base section

16 base wave

18 bite element

20 basic axis of rotation

22 Bite mounting element 4 Detector holder

26 projection surface 8 positioning element

30 central beam

32 first or primary bite surface 4 second or secondary bite surface 6 positioning bar 8 shadow reference element 0 X-ray tube 2 tooth 4 vertical 6 palatal arch 8 reference shadows 20 computer environment 22 processor unit 24 system memory 26 system bus 28 random access memory (RAM) 30 read-only memory (ROM) 132 Hard disk drive

134 disk drive

136 removable disc

138 Hard disk drive interface

140 disk drive interface

142 external disc

144 application program

146 program data

148 keyboard

150 computer mouse / trackball

152 serial interface

154 parallel interface

156 printers

158 monitor

160 video input / output

162 remote computer

164 "local area network" (LAN)

166 Wide Area Network (WAN)

168 Network input / output

Claims

claims Anspruch [en] A holding apparatus for creating intraoral shadow images, comprising: a device base configured to set a determinable position of a projection surface of a radiation detector relative to a radiation source; and a bite member rotatably mounted on the device base about a base rotational axis and including a shadow reference member such that the shadow reference member does not have continuous rotational symmetry with respect to an axis parallel to the base rotational axis. 2. The fixture of claim 1, wherein the device base comprises a detector holder for holding a radiation detector disposed on a first base portion of the device base such that the position of the projection surface of a radiation detector relative to the base axis of rotation is changeable or adjustable. 3. The fixture of claim 2, wherein the first base portion comprises: a detector pitch scale for reading an adjustable linear position of the detector holder relative to the base axis of rotation; and / or a detector angle scale for reading a variable angle of the detector holder relative to the first base portion. 4. Holding device according to claim 2 or 3, wherein the first base section comprises: a detector pitch sensor for automatically determining a variable linear position of the detector holder relative to the base axis of rotation; and / or a detector angle sensor for automatically determining a variable angle of the detector holder relative to the first base portion. 5. Holding device according to one of the preceding claims, wherein the device base comprises a positioning element for applying and / or fixing a radiation source, which is arranged on a second base portion of the device base such that the position of the radiation source relative to the base rotational axis is variable or adjustable. 6. Holding device according to claim 5, wherein the positioning element comprises a positioning ring, which is designed for applying and adjusting an X-ray tube. The fixture of claim 5 or 6, wherein the second base portion comprises: a source pitch scale for reading an adjustable linear position of the positioning member relative to the base rotational axis; and / or a source angle scale for reading a variable or adjustable angle of the positioning relative to the second base portion. 8. The fixture of claim 5, wherein the second base portion comprises: a source pitch sensor for automatically determining a variable linear position of the positioning member relative to the base rotational axis; and / or a source angle sensor for automatically determining a variable angle of the positioning member relative to the second base portion. 9. A bite element for a holding device for producing intraoral shadow recordings, in particular for a holding device according to one of the preceding claims, comprising: a bite block having a first bite surface and a second bite surface, the bite block rotatable about a base rotational axis of the bite block to a device base the holding device can be mounted or fastened; a shadow reference element which is firmly connected or firmly connectable to the bite block such that it has no continuous rotational symmetry with respect to an axis parallel to the base axis of rotation. 10. bite element according to claim 9, wherein the shadow reference element comprises metal, in particular iron and / or tungsten and / or gold and / or lead. 11. bite element according to claim 9 or 10, wherein the shadow reference element has no higher rotational symmetry than a symmetry with respect to a rotation about an axis parallel to the base axis of rotation axis by 180 °. The bite element of any one of claims 9 to 11, wherein the shadow reference member comprises a wire section having a length in the range of about 0.5 mm to about 15 mm, preferably in the range of about 1 mm to about 10 mm, more preferably in the range of about 2 mm to about 6 mm, and / or a thickness in the range of about 0.1 mm to about 2 mm, preferably in the range of about 0.2 mm to about 1 mm, more preferably in the range of about 0.5 mm to about 1 mm. 13. bite element according to one of claims 9 to 12, wherein the shadow reference element is arranged in a plane parallel to the base axis of rotation, in particular to the first and / or second Aufbissfläche or parallel and / or extending through the base axis of rotation plane. 14. bite element according to one of claims 9 to 13, wherein the shadow reference element comprises a first longitudinal portion in the form of a straight wire element having a certain or determinable length, which lies in a plane perpendicular to the base axis of rotation. 15. bite element according to one of claims 9 to 14, wherein the shadow reference element comprises a first transverse section in the form of a straight wire element having a certain or determinable length, which lies on a straight line parallel to the base axis of rotation. 16. bite element according to claim 15, wherein the shadow reference element comprises a second transverse section in the form of a straight wire element with a certain or determinable length, which is in a direction parallel to the base axis of rotation straight line on which the first transverse section is not. 17. A method for processing intraoral shadow image data comprising: Providing primary image data of an intraoral shadow image; Providing shadow reference data defining dimensions of a shadow reference element; Detecting a shape and / or size of a reference shadow of the shadow reference element defined in the primary image data; and Determining scaling data defining a scaling of the shape and / or size of the reference shadow relative to the dimensions of the shadow reference element defined in the shadow reference data. 18. The method of claim 17, wherein determining scaling data comprises determining a rotation angle. The method of claim 17 or 18, wherein said obtaining scaling data comprises determining a magnification. 20. The method of claim 17, comprising determining secondary image data by scaling the primary image data using the scaling data. 21. The method of claim 20, comprising visually displaying a secondary shadow image in response to the secondary image data. 22. The method according to claim 17, wherein providing primary image data comprises using a holding device according to one of claims 1 to 8, in particular with a bite element according to one of claims 9 to 16 for creating a primary intraoral shadow image, in particular X-ray image. 23. The method of claim 22, wherein detecting the primary intraoral shadow image pickup comprises detecting an adjustable linear position of the detector holder and / or the projection surface relative to the base rotational axis; and / or detecting an adjustable angle of the detector holder and / or the projection surface relative to the first base portion; and / or detecting an adjustable linear position of the positioning member relative to the base rotational axis; and / or detecting an adjustable angle of the positioning member relative to the second base portion. A computer program product comprising program code loaded and executed in a computer system causing said computer system to carry out a method according to any one of claims 17 to 23. 25. A system for creating and / or processing intraoral shadow images comprising a shadow image capture device for acquiring primary image data of an intraoral shadow image projected on a projection surface; a reference shadow detection module for detecting a shape and / or size of a reference shadow of a shadow reference element defined in the primary image data; and a reference shadow analysis module for determining scaling data defining a scaling of the detected shape and / or size of the reference shadow relative to dimensions of the shadow reference element. 26. The system of claim 25, further comprising a shadow scaling module configured to determine secondary image data by scaling the primary image data using the scaling data. 27. The system of claim 26, further comprising an image output unit configured to output a secondary shadow based on the secondary image data.