WO2017133844A1 - Use of a marker for determining the projection geometry of an x-ray ct device, and fixing device for a test object in an x-ray ct method - Google Patents

Use of a marker for determining the projection geometry of an x-ray ct device, and fixing device for a test object in an x-ray ct method Download PDF

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Publication number
WO2017133844A1
WO2017133844A1 PCT/EP2017/000138 EP2017000138W WO2017133844A1 WO 2017133844 A1 WO2017133844 A1 WO 2017133844A1 EP 2017000138 W EP2017000138 W EP 2017000138W WO 2017133844 A1 WO2017133844 A1 WO 2017133844A1
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Prior art keywords
ray
test object
marker
fixing device
projection
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PCT/EP2017/000138
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German (de)
French (fr)
Inventor
Frank Herold
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Yxlon International Gmbh
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Priority to PCT/EP2017/000138 priority Critical patent/WO2017133844A1/en
Priority to DE112017000672.4T priority patent/DE112017000672A5/en
Publication of WO2017133844A1 publication Critical patent/WO2017133844A1/en

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/003—Reconstruction from projections, e.g. tomography
    • G06T11/005—Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G06T7/73—Determining position or orientation of objects or cameras using feature-based methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/30—Accessories, mechanical or electrical features
    • G01N2223/33—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts
    • G01N2223/3307—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts source and detector fixed; object moves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/40—Imaging
    • G01N2223/401—Imaging image processing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/40—Imaging
    • G01N2223/419—Imaging computed tomograph
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10072—Tomographic images
    • G06T2207/10081—Computed x-ray tomography [CT]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30204—Marker
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2211/00—Image generation
    • G06T2211/40—Computed tomography
    • G06T2211/416—Exact reconstruction

Definitions

  • the invention is concerned with the use of at least one marker for determining the projection geometry of an X-ray CT apparatus and with a fixing device for a test object in an X-ray CT method.
  • Three-dimensional space is not trivial.
  • the position of the structure of such a test object becomes ambiguous through a projective mapping into two-dimensional space. Projective images of transparent test object occur in the
  • projection Hereafter referred to as projection.
  • the projection geometry describes the relative position of the test object to the focus of an X-ray source and an X-ray detector.
  • the projections used lie on a circle around the test object.
  • the path of the focal point of the X-ray source is referred to here as a trajectory or more precisely as a circle trajectory.
  • the projection geometry will be using global parameters
  • Projection geometry of each projection in contrast to global parameters for a more accurate three-dimensional image of the test object, so that, for example, dimensionally measured with a smaller
  • Measurement uncertainty can be determined.
  • Markers are - in general terms - special objects with known properties. In principle they must not be transparent to one
  • a marker can also be a composite of individual objects.
  • a marker is understood to mean an object that has at least one image feature that is at each
  • Projection geometry from a projection at least three image features must be determined. These image features may be present either within a single object (e.g., the corners of a triangle) or formed on multiple objects (eg, three spheres).
  • the position of markers in a projection must be able to be determined with subpixel accuracy, based on the pixels of the X-ray detector used, regardless of the current projection direction. Deviations in the
  • Transillumination images are not known exactly, these can be individual Transillumination images in the context of the reconstruction by means of a CT method not without artifacts to a three-dimensional image
  • the object of the invention is therefore to show solutions, such as
  • Projection geometries of the individual fluoroscopic images can be determined with sufficient accuracy to minimize artifacts in the
  • markers for determining the projection geometries for the three-dimensional reconstruction of the individual fluoroscopy images are used in an X-ray CT method. In order to avoid artifacts in the projection, they must be transparent in contrast to the non-transparent markers regularly used in other methods.
  • a marker can be used for position determination in three-dimensional space, as long as it is possible to determine three known positions which must not lie in the plane of the trajectory. The relative distances of the positions to each other must be known. If the relative position of the marker / markers to the object - which must not change in the course of the CT procedure - has been determined in advance, its location in the individual fluoroscopic images can be clearly assigned to the respective
  • the relative distances between individual markers or the feature points of a complex marker with at least three spatially independent feature points can for example be previously determined by tactile or optical methods - assuming that the distances remain constant for the duration of the determination of the projection geometries.
  • the markers must therefore be fixed with respect to the test object.
  • a combination of individual, possibly different markers By determining the position of the markers in each projection of a trajectory, the deviations from the desired projection geometry can be determined.
  • the shapes of the markers can be tailored to the inspection task or the
  • Test object can be adjusted if - as described above - the position of the marker / markers in three-dimensional space can be determined / can.
  • An advantageous development of the invention provides that the at least one marker on a robot arm of an industrial robot, which serves as a manipulator for the test object and is connected thereto, is mounted in the region of the connection between the robot arm and the test object. This ensures a fixed spatial relationship of the marker / markers to the test object and to the manipulator.
  • a further advantageous development of the invention provides that the at least one marker is attached to a fixing device for the test object, which can be connected to a robot arm of an industrial robot and to which the test object can be fixed.
  • a fixing device for the test object which can be connected to a robot arm of an industrial robot and to which the test object can be fixed.
  • a further advantageous development of the invention provides that the material of the at least one marker has a mass attenuation coefficient, which is significantly different from that of the test object, in particular by at least 20% deviates from this. This ensures that the fluoroscopic image shows a clear difference between the image of the marker (s) and the structures of the test object.
  • the at least one marker is spherical or cylindrical.
  • An extremely suitable shape for a marker is a sphere, because the center of gravity of a sphere is due to the
  • Point symmetry can be accurately determined from all projection directions and balls can be machined very precisely.
  • Cylinders are also simple and accurate to manufacture and have a high degree of symmetry - albeit not as high as that of a sphere - on. Cylinders are for certain
  • Fixing device is a rod, a mesh basket or a hollow body, in particular in the form of a cylinder.
  • the fixing device must be suitable to fix the test object, the individual markers advantageously
  • fixation of the test object can be done for example by positive or negative pressure or by
  • a cylinder is an advantageous shape; this can be designed as a barrel-shaped vessel.
  • a further advantageous development of the invention provides that two of the markers have as far as possible a distance from each other, but during the examination lie in the beam path of the x-ray tube that they are still detected in the x-ray detector.
  • the markers are imaged near the edges of the projection, and thus the relative distances from remotely located markers used. If the markers are not clearly identifiable or symmetrical - or not symmetrically arranged - not all need
  • a further advantageous embodiment provides that the at least one marker is firmly connected to the manipulation system, which moves the test object within the X-ray beam. In this way it can be estimated before the projection which markers are imaged in the projection

Abstract

The invention relates to the use of at least one marker for determining the projection geometry of an X-ray CT device, which has an X-ray source with a focus function, an X-ray detector, and a test object located between the X-ray source and the X-ray detector, during a non-destructive examination of a test object using an X-ray CT method. The at least one marker consists of a material which is transparent to X-rays and is stationary relative to a test object while the X-ray CT method is being carried out, said test object be moved within the X-ray CT device by a manipulator. The invention also relates to a fixing device for a test object in an X-ray CT method, said device being made of a material which has a mass weakening coefficient that is as low as possible and on which at least one marker is attached in a stationary manner, wherein the marker consists of a material which is transparent to X-rays.

Description

Verwendung eines Markers zur Bestimmung der Projektionsgeometrie einer Röntgen-CT-Vorrichtung sowie Festlegevorrichtung für ein Prüfobjekt bei einem  Use of a marker for determining the projection geometry of an X-ray CT apparatus and fixing device for a test object in a
Röntgen-CT-Verfahren  X-ray CT method
Die Erfindung befasst sich mit der Verwendung mindestens eines Markers zur Bestimmung der Projektionsgeometrie einer Röntgen-CT-Vorrichtung sowie mit einer Festlegevorrichtung für ein Prüfobjekt bei einem Röntgen-CT-Verfahren. The invention is concerned with the use of at least one marker for determining the projection geometry of an X-ray CT apparatus and with a fixing device for a test object in an X-ray CT method.
Die Bestimmung der Lage eines röntgentransparenten Prüfobjektes im The determination of the position of an X - ray transparent test object in
dreidimensionalen Raum ist nicht trivial. Die Lage der Struktur eines solchen Prüfobjekts wird durch eine projektive Abbildung in den zweidimensionalen Raum mehrdeutig. Projektive Abbildungen transparenter Prüfobjekt treten in der Three-dimensional space is not trivial. The position of the structure of such a test object becomes ambiguous through a projective mapping into two-dimensional space. Projective images of transparent test object occur in the
Röntgen-Bildgebung als Standardanwendung auf, da hier diese Eigenschaft verwendet wird, um innere Strukturen sichtbar zu machen, die bei visueller Betrachtung undurchsichtig sind. Diese projektiven Abbildungen werden im X-ray imaging as a standard application, since this property is used to visualize internal structures that are opaque when viewed visually. These projective pictures will be published in
Folgenden kurz als Projektion bezeichnet. Hereafter referred to as projection.
Zur dreidimensionalen Rekonstruktion eines röntgentransparenten Objektes aus Projektionen unterschiedlicher Projektionsrichtungen ist eine exakte Kenntnis der Projektionsgeometrie erforderlich. Im Sinne der Röntgen-Bildgebung beschreibt die Projektionsgeometrie die relative Lage des Prüfobjekts zum Fokus einer Röntgenquelle und einem Röntgendetektor. For the three-dimensional reconstruction of an X-ray-transparent object from projections of different projection directions, an exact knowledge of the projection geometry is required. In terms of X-ray imaging, the projection geometry describes the relative position of the test object to the focus of an X-ray source and an X-ray detector.
Typischerweise liegen die verwendeten Projektionen auf einem Kreis um das Prüfobjekt. Die Strecke des Fokuspunktes der Röntgenquelle wird hierbei als Trajektorie beziehungsweise genauer als Kreistrajektorie bezeichnet. Typically, the projections used lie on a circle around the test object. The path of the focal point of the X-ray source is referred to here as a trajectory or more precisely as a circle trajectory.
Standardmäßig wird die Projektionsgeometrie mit globalen Parametern By default, the projection geometry will be using global parameters
beschrieben; beispielsweise gilt im Falle einer Kreistrajektorie für alle Projektion die gleiche Schiefstellung des Detektors. Verfahren, die die Projektionsgeometrie für jede Projektion entlang der Trajektorie bestimmen, sind selten, wenig robust und nur für eine bestimmte Trajektorie verwendbar. Für eine Kreistrajektorie funktionieren solche Verfahren in den meisten Fällen; für komplexere Trajektorien, wie beispielsweise eine Helix-förmige Trajektorie regelmäßig nicht. Unabhängig von der gewählten Trajektorie führt die Verwendung der exakten described; For example, in the case of a circular trajectory, the same misalignment of the detector applies to all projections. Methods that determine the projection geometry for each projection along the trajectory are rare, less robust and usable only for a particular trajectory. For a circle trajectory, such methods work in most cases; for more complex trajectories, such as a helical-shaped trajectory regularly not. Regardless of the chosen trajectory, the use of the exact leads
Projektionsgeometrie jeder einzelnen Projektion im Gegensatz zu globalen Parametern zu einer exakteren dreidimensionalen Abbildung des Prüfobjektes, so dass beispielsweise dimensioneile Messgrößen mit einer geringeren Projection geometry of each projection in contrast to global parameters for a more accurate three-dimensional image of the test object, so that, for example, dimensionally measured with a smaller
Messunsicherheit bestimmt werden können. Measurement uncertainty can be determined.
Stereoskopische Ansätze, die sich für nichttransparente Objekte etabliert haben - solche Verfahren werden beispielsweise mit Auflichtmikroskopen durchgeführt -, sind mit transparenten Objekten aufgrund der oben genannten Mehrdeutigkeit der Lage der Strukturen des Prüfobjekts nicht anwendbar. Stereoscopic approaches that have established themselves for nontransparent objects - such methods are performed, for example, with incident light microscopes - are not applicable to transparent objects due to the above-mentioned ambiguity of the position of the structures of the test object.
Marker sind - ganz allgemein ausgedrückt - spezielle Objekte mit bekannten Eigenschaften. Sie dürfen prinzipiell nicht transparent sein, um eine Markers are - in general terms - special objects with known properties. In principle they must not be transparent to one
Mehrdeutigkeit auszuschließen. Ein zu prüfendes, beziehungsweise zu To exclude ambiguity. One to be tested, or to
messendes Prüfobjekt weist eine unbekannte Dimension, Fehler oder auch Fertigungstoleranzen auf. Das Prüfobjekt ist somit in der Regel nicht als Marker geeignet. Prinzipiell kann ein Marker auch ein Verbund aus einzelnen Objekten sein. Im Rahmen dieser Anmeldung wird unter einem Marker ein Objekt verstanden, das mindestens ein Bildmerkmal aufweist, das bei jeder measuring test object has an unknown dimension, error or manufacturing tolerances. The test object is thus generally not suitable as a marker. In principle, a marker can also be a composite of individual objects. In the context of this application, a marker is understood to mean an object that has at least one image feature that is at each
durchgeführten Projektion eindeutig lokalisierbar ist. Zur Bestimmung der Projection is clearly localized. To determine the
Projektionsgeometrie aus einer Projektion müssen mindestens drei Bildmerkmale bestimmt werden können. Diese Bildmerkmale können entweder innerhalb eines einzelnes Objekts vorhanden sein (beispielsweise die Ecken eines Dreiecks) oder an mehreren Objekten ausgebildet sein (beispielsweise drei Kugeln). Projection geometry from a projection, at least three image features must be determined. These image features may be present either within a single object (e.g., the corners of a triangle) or formed on multiple objects (eg, three spheres).
Die Position von Markern in einer Projektion muss subpixelgenau - bezogen auf die Pixel des verwendeten Röntgendetektors - bestimmt werden können, unabhängig von der aktuellen Projektionsrichtung. Abweichungen bei der The position of markers in a projection must be able to be determined with subpixel accuracy, based on the pixels of the X-ray detector used, regardless of the current projection direction. Deviations in the
Positionsbestimmung führen zu signifikanten Fehlern hinsichtlich der Positioning leads to significant errors in terms of
Projektionsgeometrie. Wenn die Projektionsgeometrie der einzelnen Projection geometry. If the projection geometry of each
Durchleuchtungsbilder nicht genau bekannt ist, können diese einzelnen Durchleuchtungsbilder im Rahmen der Rekonstruktion mittels eines CT- Verfahrens nicht ohne Artefakte zu einem dreidimensionalen Bild Transillumination images are not known exactly, these can be individual Transillumination images in the context of the reconstruction by means of a CT method not without artifacts to a three-dimensional image
zusammengefügt werden. be joined together.
Aufgabe der Erfindung ist es deshalb, Lösungen aufzuzeigen, wie The object of the invention is therefore to show solutions, such as
Projektionsgeometrien der einzelnen Durchleuchtungsbilder mit hinreichender Genauigkeit ermittelt werden können, um möglichst wenig Artefakte im Projection geometries of the individual fluoroscopic images can be determined with sufficient accuracy to minimize artifacts in the
rekonstruierten dreidimensionalen Bild eines Prüfteils zu erzeugen. reconstructed three-dimensional image of a test piece to produce.
Die Aufgabe wird durch eine Verwendung gemäß den Merkmalen des The object is achieved by a use according to the characteristics of
Patentanspruchs 1 gelöst. Erfindungsgemäß werden Marker zur Ermittlung der Projektionsgeometrien zur dreidimensionalen Rekonstruktion der einzelnen Durchleuchtungsbilder in einem Röntgen-CT-Verfahren eingesetzt. Hierzu müssen diese abweichend von dem in anderen Verfahren regelmäßig verwendeten intransparenten Markern transparent sein, um Artefakte in der Projektion gering zu halten. Ein Marker kann zur Lagebestimmung im dreidimensionalen Raum verwendet werden, sofern es möglich ist, damit drei bekannte Positionen zu bestimmen, die nicht in der Ebene der Trajektorie liegen dürfen. Die relativen Abstände der Positionen zueinander müssen bekannt sein. Wenn die relative Position des Markers/der Marker zum Objekt - die sich im Laufe des CT- Verfahrens nicht ändern darf - im Vorfeld genau bestimmt wurde, kann aus deren Lage in den einzelnen Durchleuchtungsbildern eindeutig auf die jeweilige Patent claim 1 solved. According to the invention, markers for determining the projection geometries for the three-dimensional reconstruction of the individual fluoroscopy images are used in an X-ray CT method. In order to avoid artifacts in the projection, they must be transparent in contrast to the non-transparent markers regularly used in other methods. A marker can be used for position determination in three-dimensional space, as long as it is possible to determine three known positions which must not lie in the plane of the trajectory. The relative distances of the positions to each other must be known. If the relative position of the marker / markers to the object - which must not change in the course of the CT procedure - has been determined in advance, its location in the individual fluoroscopic images can be clearly assigned to the respective
Projektionsgeometrie rückgeschlossen werden und eine korrekte Rekonstruktion des Prüfobjekts - sofern dieses über den gesamten Prüfungszeitraum an dem Manipulator festgelegt ist - erfolgen. Dies ist auch erfüllt, wenn sowohl der Marker als auch das Objekt am Manipulator befestigt sind. Die relativen Abstände zwischen einzelnen Markern beziehungsweise den Merkmalspunkten eines komplexen Markers mit mindesten drei räumlich unabhängigen Merkmalspunkten können beispielsweise durch taktile oder optische Methoden vorher einmalig bestimmt werden - unter der Annahme, dass die Abstände für die Dauer der Bestimmung der Projektionsgeometrien konstant bleiben. Die Marker müssen somit fix bezüglich des Prüfobjekts angebracht sein. Erfindungsgemäß ist auch eine Kombination aus einzelnen, gegebenenfalls unterschiedlichen Markern. Durch Bestimmung der Lage der Marker in jeder Projektion einer Trajektorie, können die Abweichungen von der Soll-Projektionsgeometrie bestimmt werden. Daher ist es möglich, neben einer Kreistrajektorie, auch komplexere Trajektorien, beispielsweise in der Form einer Helix oder einer Kombination aus einem Kreis und einer Linie bis hin zu beliebigen Trajektorien, exakt zu vermessen und bestmöglich dreidimensional zu rekonstruieren. Grundsätzlich können die Formen der Marker individuell auf die Inspektionsaufgabe beziehungsweise das Projection geometry and a correct reconstruction of the test object - if this is determined over the entire examination period on the manipulator - done. This is also true when both the marker and the object are attached to the manipulator. The relative distances between individual markers or the feature points of a complex marker with at least three spatially independent feature points can for example be previously determined by tactile or optical methods - assuming that the distances remain constant for the duration of the determination of the projection geometries. The markers must therefore be fixed with respect to the test object. Also according to the invention a combination of individual, possibly different markers. By determining the position of the markers in each projection of a trajectory, the deviations from the desired projection geometry can be determined. Therefore, in addition to a circular trajectory, it is also possible to precisely measure complex trajectories, for example in the form of a helix or a combination of a circle and a line up to arbitrary trajectories, and reconstruct them in the best possible three-dimensional manner. Basically, the shapes of the markers can be tailored to the inspection task or the
Prüfobjektes angepasst werden, sofern - wie oben beschrieben - die Lage des Markers/der Marker im dreidimensionalen Raum bestimmt werden kann/können. Test object can be adjusted if - as described above - the position of the marker / markers in three-dimensional space can be determined / can.
Eine vorteilhafte Weiterbildung der Erfindung sieht vor, dass der mindestens eine Marker an einem Roboterarm eines Industrieroboters, der als Manipulator für das Prüfobjekt dient und mit diesem verbunden ist, im Bereich der Verbindung zwischen dem Roboterarm und dem Prüfobjekt angebracht ist. Dadurch ist eine feste räumliche Beziehung des Markers/der Marker zum Prüfobjekt und zum Manipulator sichergestellt. An advantageous development of the invention provides that the at least one marker on a robot arm of an industrial robot, which serves as a manipulator for the test object and is connected thereto, is mounted in the region of the connection between the robot arm and the test object. This ensures a fixed spatial relationship of the marker / markers to the test object and to the manipulator.
Eine weitere vorteilhafte Weiterbildung der Erfindung sieht vor, dass der mindestens eine Marker an einer Festlegevorrichtung für das Prüfobjekt, die mit einem Roboterarm eines Industrieroboters verbindbar und an der das Prüfobjekt festlegbar ist, angebracht ist. Dadurch kann bei der Prüfung ein Industrieroboter verwendet werden, der komplexere Bewegungsbahnen des Prüfobjekts während der Prüfung ermöglicht, als ein konventioneller Manipulationstisch mit A further advantageous development of the invention provides that the at least one marker is attached to a fixing device for the test object, which can be connected to a robot arm of an industrial robot and to which the test object can be fixed. As a result, an industrial robot can be used in the test, which allows more complex trajectories of the test object during the test, as a conventional manipulation table with
Linearachsen und Drehtisch. Linear axes and turntable.
Die Aufgabe wird auch durch eine Festlegevorrichtung mit den Merkmalen des Patentanspruchs 4 gelöst. Es ergeben sich auch hierfür die oben zur The object is also achieved by a fixing device with the features of claim 4. There are also the above for
erfindungsgemäßen Verwendung angegeben Vorteile. use according to the invention indicated advantages.
Eine weitere vorteilhafte Weiterbildung der Erfindung sieht vor, dass das Material des mindestens einen Markers einen Massenschwächungskoeffizienten aufweist, der deutlich verschieden von demjenigen des Prüfobjekts ist, insbesondere um mindestens 20% von diesem abweicht. Dadurch wird gewährleistet, dass man im Durchleuchtungsbilds einen deutlichen Unterschied zwischen der Abbildung des Markers/der Marker und den Strukturen des Prüfobjekts erkennt. A further advantageous development of the invention provides that the material of the at least one marker has a mass attenuation coefficient, which is significantly different from that of the test object, in particular by at least 20% deviates from this. This ensures that the fluoroscopic image shows a clear difference between the image of the marker (s) and the structures of the test object.
Eine vorteilhafte Weiterbildung der Erfindung sieht vor, dass der mindestens eine Marker kugelförmig oder zylinderförmig ist. Eine äußerst geeignete Form für einen Marker ist eine Kugel, da der Schwerpunkt einer Kugel aufgrund der An advantageous development of the invention provides that the at least one marker is spherical or cylindrical. An extremely suitable shape for a marker is a sphere, because the center of gravity of a sphere is due to the
Punktsymmetrie aus allen Projektionsrichtungen exakt bestimmt werden kann und Kugeln mechanisch sehr präzise gefertigt werden können. Zylinder sind ebenfalls einfach und präzise zu fertigen und weisen einen hohen Symmetriegrad - wenn auch nicht so hoch wie jener einer Kugel - auf. Zylinder sind für bestimmte Point symmetry can be accurately determined from all projection directions and balls can be machined very precisely. Cylinders are also simple and accurate to manufacture and have a high degree of symmetry - albeit not as high as that of a sphere - on. Cylinders are for certain
Anwendungen gut geeignet, beispielsweise zur Rekonstruktion einer einzelnen Schicht des Prüfobjekts. Applications well suited, for example, to reconstruct a single layer of the test object.
Eine weitere vorteilhafte Weiterbildung der Erfindung sieht vor, dass die A further advantageous embodiment of the invention provides that the
Festlegevorrichtung eine Stange, ein Gitterkorb oder ein Hohlkörper, insbesondere in der Form eines Zylinders, ist. Die Festlegevorrichtung muss geeignet sein, das Prüfobjekt zu fixieren, wobei die einzelnen Marker vorteilhafterweise Fixing device is a rod, a mesh basket or a hollow body, in particular in the form of a cylinder. The fixing device must be suitable to fix the test object, the individual markers advantageously
größtmögliche Abstände zueinander haben. Die Fixierung des Prüfobjekts kann beispielsweise durch Über- oder Unterdruck geschehen oder durch have the greatest possible distance from each other. The fixation of the test object can be done for example by positive or negative pressure or by
entsprechendes Füllmaterial oder konventionelle Befestigungsvorrichtungen wie Gurte. Für eine Kreistrajektorie ist ein Zylinder eine vorteilhafte Form; dieser kann als tonnenförmiges Gefäß ausgebildet sein. appropriate filling material or conventional fastening devices such as belts. For a circular trajectory, a cylinder is an advantageous shape; this can be designed as a barrel-shaped vessel.
Eine weitere vorteilhafte Weiterbildung der Erfindung sieht vor, dass zwei der Marker einen möglichst weiten Abstand voneinander aufweisen, aber während der Untersuchung so im Strahlengang der Röntgenröhre liegen, dass sie noch im Röntgendetektor erfasst werden. Je größer der Abstand zwischen zwei Markern ist, desto genauer kann der Abstand der Marker auf der Projektion gemessen werden. Idealerweise werden die Marker daher nahe den Rändern der Projektion abgebildet und somit die relativen Abstände von weitentfernten Markern verwendet. Sofern die Marker nicht eindeutig identifizierbar oder symmetrisch sind - beziehungsweise nicht symmetrisch angeordnet sind -, müssen nicht alle A further advantageous development of the invention provides that two of the markers have as far as possible a distance from each other, but during the examination lie in the beam path of the x-ray tube that they are still detected in the x-ray detector. The larger the distance between two markers, the more accurate the distance of the markers on the projection can be measured. Ideally, therefore, the markers are imaged near the edges of the projection, and thus the relative distances from remotely located markers used. If the markers are not clearly identifiable or symmetrical - or not symmetrically arranged - not all need
Marker in jeder Projektion sichtbar sein. Dies bedeutet, dass die Marker Markers be visible in every projection. This means that the markers
beispielsweise an einem Kasten angebracht sein können, der auch aus dem Projektionsbereich herausragen kann. for example, may be attached to a box, which may also protrude from the projection area.
Eine weitere vorteilhafte Weiterbildung sieht vor, dass der mindestens eine Marker fest mit dem Manipulationssystem verbunden ist, welches das Prüfobjekt innerhalb des Röntgenstrahls bewegt. Dadurch kann vor der Projektion abgeschätzt werden, welche Marker in der Projektion abgebildet werden A further advantageous embodiment provides that the at least one marker is firmly connected to the manipulation system, which moves the test object within the X-ray beam. In this way it can be estimated before the projection which markers are imaged in the projection

Claims

Patentansprüche claims
1. Verwendung mindestens eines Markers zur Bestimmung der 1. Use of at least one marker for the determination of
Projektionsgeometrie einer Röntgen-CT- Vorrichtung, die eine Röntgenquelle mit Fokus, einen Röntgendetektor und ein dazwischen befindliches  Projection geometry of an X-ray CT apparatus, which has a focus X-ray source, an X-ray detector and an intervening
Prüfobjekt aufweist, während einer zerstörungsfreien Untersuchung eines Prüfobjekts mittels eines Röntgen-CT-Verfahrens, wobei der mindestens eine Marker aus einem für Röntgenstrahlen transparenten Material besteht und während der Durchführung des Röntgen-CT-Verfahrens ortsfest zu einem Prüfobjekt ist, welches durch einen Manipulator innerhalb der Röntgen-CT- Vorrichtung bewegt wird.  Test object, during a non-destructive examination of a test object by means of an X-ray CT method, wherein the at least one marker from a transparent material for X-rays and while performing the X-ray CT method is stationary to a test object, which by a manipulator within the X-ray CT apparatus is moved.
2. Verwendung nach Patentanspruch 1 , wobei der mindestens eine Marker an einem Roboterarm eines Industrieroboters, der als Manipulator für das Prüfobjekt dient und mit diesem verbunden ist, im Bereich der Verbindung zwischen dem Roboterarm und dem Prüfobjekt angebracht ist. 2. Use according to claim 1, wherein the at least one marker on a robot arm of an industrial robot, which serves as a manipulator for the test object and is connected thereto, is mounted in the region of the connection between the robot arm and the test object.
3. Verwendung nach einem der vorstehenden Patentansprüche, wobei der mindestens eine Marker an einer Festlegevorrichtung für das Prüfobjekt, die mit einem Roboterarm eines Industrieroboters verbindbar und an der das Prüfobjekt festlegbar ist, angebracht ist. 3. Use according to one of the preceding claims, wherein the at least one marker on a fixing device for the test object, which is connectable to a robot arm of an industrial robot and on which the test object can be fixed, is mounted.
4. Festlegevorrichtung für ein Prüfobjekt bei einem Röntgen-CT-Verfahren aus einem Material mit einem möglichst geringen 4. Fixing device for a test object in an X-ray CT method of a material with the lowest possible
Massenschwächungskoeffizienten, an dem ortsfest mindestens ein Marker angebracht ist, der aus einem für Röntgenstrahlen transparenten Material besteht.  Mass attenuation coefficients to which at least one marker consisting of an X-ray transparent material is fixedly attached.
5. Verwendung oder Festlegevorrichtung nach einem der vorstehenden 5. Use or fixing device according to one of the preceding
Patentansprüche, wobei das Material des mindestens einen Markers einen Massenschwächungskoeffizienten aufweist, der deutlich verschieden von demjenigen des Prüfobjekts ist, insbesondere um mindestens 20% von diesem abweicht. Claims, wherein the material of the at least one marker has a mass attenuation coefficient which is significantly different from that of the test object, in particular by at least 20% deviates from this.
6. Verwendung oder Festlegevorrichtung nach einem der vorstehenden 6. Use or fixing device according to one of the preceding
Patentansprüche, wobei der mindestens eine Marker kugelförmig oder zylinderförmig ist.  Claims, wherein the at least one marker is spherical or cylindrical.
7. Verwendung oder Festlegevorrichtung nach einem der Patentansprüche 3 bis 6, wobei die Festlegevorrichtung eine Stange, ein Gitterkorb oder ein Hohlkörper, insbesondere in der Form eines Zylinders, ist. 7. Use or locking device according to one of the claims 3 to 6, wherein the fixing device is a rod, a mesh basket or a hollow body, in particular in the form of a cylinder.
8. Verwendung oder Festlegevorrichtung nach einem der vorstehenden 8. Use or fixing device according to one of the preceding
Patentansprüche, wobei zwei der Marker einen möglichst weiten Abstand voneinander aufweisen, aber während der Untersuchung so im Strahlengang der Röntgenröhre liegen, dass sie noch im Röntgendetektor erfasst werden.  Claims, wherein two of the markers have the greatest possible distance from each other, but during the investigation lie in the beam path of the X-ray tube that they are still detected in the X-ray detector.
9. Verwendung oder Festlegevorrichtung nach einem der vorstehenden 9. Use or fixing device according to one of the preceding
Patentansprüche, wobei der mindestens eine Marker fest mit dem  Claims, wherein the at least one marker fixed to the
Manipulationssystem verbunden ist, welches das Prüfobjekt innerhalb des Röntgenstrahls bewegt.  Manipulation system is connected, which moves the test object within the X-ray beam.
PCT/EP2017/000138 2016-02-04 2017-02-03 Use of a marker for determining the projection geometry of an x-ray ct device, and fixing device for a test object in an x-ray ct method WO2017133844A1 (en)

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DE112017000672.4T DE112017000672A5 (en) 2016-02-04 2017-02-03 Use of a marker for determining the projection geometry of an X-ray CT apparatus as well as a fixing device for a test object in an X-ray CT method

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DE102016001247.1 2016-02-04
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Citations (1)

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DE102012013500A1 (en) * 2012-07-06 2014-01-09 Yxlon International Gmbh Method for drawing in X-ray fluoroscopic images in the context of a digital laminography method and use of a multi-axis manipulator system for carrying out such a method

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