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    公开号:BE1020452A5
    申请号:E2012/0294
    申请日:2012-05-04
    公开日:2013-10-01
    发明作者:Michel Janssens
    申请人:Materialise Nv；
    IPC主号:
    专利说明:

    CALIBRATION DEVICE FOR IMAGE
    FIELD OF THE INVENTION
    The present invention relates to calibration devices, their use and methods for the in-line geometric correction and correction of the gray value of data obtained by imaging devices such as X-ray radiography, ultrasonography, MRI or CT.
    BACKGROUND
    Typically, medical imaging techniques such as X-ray radiography are mainly used for qualitative measurements and diagnoses, e.g. to see whether or not a bone is fractured, or to see whether or not a tumor is present. However, modern applications of X-ray imaging for quantitative measurements have given rise to new requirements with regard to the accuracy of X-ray imaging.
    First and foremost, geometric accuracy is a common problem with dimensional metrology. If the geometric accuracy of an image is excellent, then the distance between two features on an object can be unambiguously deduced from the distance between these features on the image of that object, for example, by multiplying the distances on the image by a specific scaling factor . However, due to various mechanical and optical effects, radiographic images such as X-rays can be distorted. Known effects are the cushion effect and enlargement or reduction of various body parts relative to their distance from the imaging surface. the result is that a certain distance on the image does not give an accurate estimate of the actual distance, e.g. dimensions of certain anatomical parts. Non-calibrated X-rays therefore only offer qualitative information, not quantitative information.
    A second problem is the accuracy of the gray value of radiographic images. The gray value can vary between different measurements, and even within a single measurement, for example due to inhomogeneity of the radiation source or the unstable sensitivity of the radiographic plate or detector.
    For example, due to limited accuracy, it is difficult to distinguish between a 5% increase or decrease in tumor size when comparing two radiographs of the same body part taken at different times. On the other hand, when measuring osteoporosis, it is possible to detect a bone density based on the gray values in a certain area of the image, but it is not possible to compare the gray values of this image with the values of an image that is on a taken later. In principle, this problem could be solved by using consistently calibrated X-ray cameras. In practice this is so cumbersome that it rarely happens.
    In the past, solutions have been proposed for some of these problems
    US Patent Application 2008/273665 (Rolle, Boots) describes an apparatus and method for accurately measuring the anatomy of a patient undergoing a radiographic procedure, using a sphere of known dimensions attached to a flexible member. The sphere is brought into the correct position and remains stationary during the procedure. U.S. Patent No. 6459772 (Wiedenhoefer et al.) Describes a radiographic reference marker, comprising a sphere of known size, which is contained in a radiolucent housing. The sphere is attached to a patient in the same plane as the anatomical target of the X-rays. Although these inventions can be used to determine the magnification or reduction of image, they do not allow a more accurate correction of the geometric distortions in the image, and the high radio opacity of the markers does not permit a correction of the gray value. Moreover, while these devices offer a high degree of freedom for positioning the marker relative to the body, they do not provide a means to do this in a reproducible manner. In addition, these techniques only offer reference markers in a zone of the image.
    U.S. Patent No. 5951475 (Gueziec et al.) Describes methods and a system for geometrically calibrating X-ray projection images using a calibration device that includes radiopaque markers, wherein the calibration device can be manipulated by a robot. However, this system requires special and expensive equipment, and further requires the acquisition of multiple images of the relevant area. Moreover, the system only allows geometric calibration, no correction of the gray levels.
    Therefore, there is a need for improved methods and instruments for image calibration.
    I *
    SUMMARY OF THE INVENTION
    The present invention relates to image calibration apparatus and methods for calibrating data obtained by imaging techniques. More in particular methods and instruments comprising (in-line) geometric correction and / or correction of the gray values of data obtained by imaging techniques such as radiography, ultrasound, computed tomography (CT) with X-rays and magnetic resonance imaging (MRI).
    In one aspect, methods for correction and / or calibration are provided with images that utilize calibration components with a specified radio opacity and geometric position. In particular embodiments, the methods may include the following steps: * I) providing an image wherein said image comprises an image of one or more sets of two or more non-identical and interconnected calibration components; and II) correcting the image based on the information obtained from the measurement of the image of the calibration components.
    The two or more non-identical and interconnected calibration components usually differ at least in radio opacity.
    In particular embodiments, at least one of the sets of calibration components comprises three or more non-identical calibration components, two or more of which are different in opacity and wherein the three or more calibration components are interconnected to form a three-dimensional geometric figure.
    In particular embodiment, step I) may include providing an image wherein the image comprises an image of one or more sets of calibration components as described herein. In certain embodiments, the methods provided are methods for correcting and / or calibrating an image of at least a portion of an area of a patient and step I) comprises the following steps: a. Applying a calibration device for medical imaging As here described on the patient in the relevant area; and B. acquiring an image of the relevant area including the calibration device for medical imaging.
    In particular embodiments, image correction methods as provided herein include a correction of the gray value of the image. In further embodiments, such methods may include the following steps: • the identification of two or more calibration components in the image; • the determination of the gray value of the identified calibration components in the image; • the calculation of the gray value error based on. the difference between the determined gray value and the calculated gray value; and • the application of the correction to the image.
    In certain embodiments, the methods may include the use of imaging calibration devices comprising one or more sets of two or more non-identical and interconnected or connectable calibration components wherein the non-identical and interconnected or connectable calibration components differ in radio opacity.
    In certain embodiments, the method of image correction according to the present invention comprises a geometric correction of the image. In further embodiments, the methods may include the following steps: • the identification of at least three calibration components in the image; • the determination of the 3D position of each calibration component; • the calculation of the geometric error on the image; and • the application of the correction to the image.
    In certain embodiments, methods for correction and / or calibration are provided with an image, which methods include the following: I) providing an image wherein said image is an image of one or more sets of two or more non-identical and interconnected or comprises connectable calibration components; and II) correcting the image based on the information obtained from the measurement of the geometry and gray values of said image of said calibration components.
    In special embodiments, image correction methods are provided which are methods for correcting images of (at least a part of) a patient and providing information about the position and shape of the patient (or a relevant part thereof) ).
    In particular embodiments, the methods for the correction and / or calibration of images provided herein are further based on the determination of errors in more than one area in the image.
    In certain embodiments, the provided image correction methods may further include the step of removing the images of the calibration components from the image. In special embodiments, the correction is an in-line correction.
    In a further aspect, medical imaging calibration devices are provided comprising a set of two or more non-identical and interconnected or connectable calibration components, wherein at least two calibration components have a radio opacity between, and not including, "0 and 1." More specifically, two or more non-identical and interconnected or connectable calibration components of the device have at least one different radio opacity. In further particular embodiments, the set comprises three or more non-identical calibration components and the set further comprises means for interconnecting the calibration components to form a fixed three-dimensional geometric figure. The set of calibration components may further comprise a means, more particularly a separate structure for placing and / or positioning the set of calibration components on the body. In particular embodiments, the interconnected calibration components have fixed, relative positions.
    The calibration devices as described herein allow a geometric correction and / or correction of the gray value of images such as medical images. More specifically, they allow a combination of geometric correction and correction of the gray value of images. In particular embodiments, the devices of the present invention allow the correction of local inhomogeneities in an object. This considerably improves the quality of the image, which is particularly interesting in the context of medical images. In particular embodiments, the medical imaging calibration apparatus as described herein can be used to improve the quality of medical images.
    In particular embodiments, the calibration devices as described herein can be used to correct the gray value of medical images. In particular embodiments, at least two calibration components in the set have different radio opacity. In certain embodiments, the calibration components are spherical.
    In particular embodiments, the centers or the longitudinal axis of the interconnected calibration components (i.e. When interconnected) form the vertices or sides of an imaginary polygon, respectively. In further embodiments, the centers of the interconnected calibration components form the vertices of an imaginary polygon. In certain embodiments, the interconnected calibration components form tetrahedron. In particular embodiments, the set of interconnected calibration components forms a multiplicity with at least one calibration component disposed within the multiplicity. In further embodiments, the set of interconnected calibration components forms a multiplicity with at least one calibration component disposed in the center of the multiplicity.
    In particular embodiments, at least one of the calibration components is hollow. In further embodiments, the ratio between the outer and inner diameter of at least one calibration component is different from the ratio between the outer and inner diameter of another calibration component.
    In certain embodiments, the outer diameter of at least one calibration component is different from the outer diameter of another calibration component.
    The calibration devices described herein can preferably be used to (independently) correct different areas in one image. In this way, local inhomogeneities in one area of the image do not affect the correction in another part of the image. To provide this, the calibration devices of the present invention include, in certain embodiments, at least two sets of calibration components.
    In certain embodiments, the calibration components are made from a polymer-containing metal, metal oxide, or metal sulfate particles.
    In particular embodiments, the described calibration devices further comprise a housing that covers at least a portion of the calibration components. In special embodiments, the housing may comprise a feature that facilitates the positioning of the device on the relevant object, such as a part of the human body. In special embodiments, the housing comprises a (patient-specific) coupling surface.
    In certain embodiments, the means for placing the set (s) of calibration components is a garment.
    In particular embodiments, the calibration components in the calibration devices of the present invention are adapted to a specific tissue type or region of the body.
    In certain embodiments, the calibration device of the present invention comprises a set of at least five non-identical spheres that have an X-ray opacity that is between, and not including, 0 and 1, the spheres being or being interconnected at such that the centers of at least four of the spheres form the angular points of an imaginary polyhedron, and one sphere is within the polyhedron. "
    A further aspect of the use of the calibration components for medical imaging as described herein is provided for the quantitative measurement on data obtained by X-rays, ultrasound, CT and MRI.
    BRIEF DESCRIPTION OF THE FIGURES
    The following description of the figures of specific embodiments of the invention is merely illustrative and is not intended to limit the present description, application or uses thereof. Corresponding to the figures; reference numbers to similar or corresponding parts and characteristics.
    Figure 1 Illustration of a radiographic image on which a radiation source (7), an X-ray beam (8), a selected area (9) and a detector (10) are shown.
    Figure 2 Calibration device for medical imaging (1) according to a particular embodiment of the present invention, comprising different sets (2) of calibration components, and a means (3) for placing the set of calibration components on the body.
    Figure 3. Set (2) of interconnected calibration components (4, 5) according to a particular embodiment of the present invention, comprising five outer calibration components (4), an inner calibration component (5) and connections (6) between the inner calibration component (5) and the outer calibration components (4). The centers of the four outer calibration components (4) form the vertices of an imaginary polyhedron, i.e. a tetrahedron. The inner calibration component (5) is located in the center of the tetrahedron.
    Figure 4 Set (2) of interconnected calibration components (4, 5) according to a particular embodiment of the present invention, comprising five outer calibration components (4), an inner calibration component (5) and connections (6) between the inner calibration component (5) and the outer calibration components (4). The centers of the five outer calibration components (4) form the vertices of an imaginary polyhedron, i.e. a (square) pyramid. The inner calibration component (5) is located in the center of the yj pyramid.
    Figure 5 Flow chart of exemplary steps in methods according to particular embodiments of the invention for in-line correction of radiographic images.
    Figure 6 A-G: Set (2) of 4 interconnected calibration components (4, 5) according to a special embodiment of the present invention provided in a housing (11).
    Figure 7 A-D: Set (2) of 4 interconnected calibration components (4, 5) according to a special embodiment of the present invention provided in a housing (11).
    Figure 8 A-D: Set (2) of 4 interconnected calibration components (4, 5) according to a special embodiment of the present invention provided in a housing (11).
    Figure 9 A, B: Configuration of various sets (2) of interconnected calibration components (4, 5) according to a special embodiment of the present invention.
    Figure 10 A-C: Set (2) of interconnected calibration components (4, 5) according to a special embodiment of the present invention provided in a housing (11).
    The following numbers are used on the figures: 1 - calibration device; 2 - set of calibration components; 3 - locators; 4, 5 calibration component; 6 - connection; 7 - radiation source; 8 - radiation beam; 9 - selected area; 10 detector; 11 - housing; 12 coupling surface; 13 lid.
    DETAILED DESCRIPTION
    The present invention will be described with respect to particular embodiments, but the invention is not limited thereby, but only by the claims. Reference characters in the claims should not be interpreted as a limitation of their scope.
    As used herein, the singular forms include "one," "the," and "raise both the singular and the plural, unless otherwise indicated in the context.
    The terms "comprising", "includes" and "consists of" as used herein are synonymous with "containing", "contains" and "inclusive and are comprehensive or indefinite and do not include additional, unnamed parts, elements or steps of the process from. The terms "comprising", "includes" also include the term "consisting of".
    In addition, the terms first, second, third and the like in the description and in the claims are used to distinguish between similar elements and not necessarily to describe a sequential or chronological order unless otherwise specified. It will be understood that the terms thus used may be interchanged in suitable circumstances and that the embodiments of the invention described herein may be used in other sequences than described or illustrated herein.
    The term "approximately" as used herein when referring to a measurable value such as a parameter, a quantity, a duration and the like, is intended to mean variations of +/- 10% or less, preferably +/- 5% or less, more preferably +/- 1% or less, and even more preferably +/- 0.1% or less than the specified value, to the extent such variations apply to the practice of the described invention. It will be clear that the value to which the provision "approximately" refers itself is also specifically, and preferably, described.
    The inclusion of numerical ranges through end points includes all digits and fractions that fall within the respective ranges, as well as the listed end points.
    »F
    All documents quoted in the present specification are hereby incorporated by reference in their entirety.
    Unless defined otherwise, all terms used in describing the invention, including technical and scientific terms, have the meaning as commonly understood by a person skilled in the art to which this invention belongs. By way of further assistance, definitions for the terms used in the description are included to better understand the description of the present invention. The terms or definitions used herein are provided only to help us understand the invention.
    Reference in this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or feature described in connection with the embodiment; included in at least one embodiment of the present invention. The sentences "in one embodiment" or "in an embodiment" at different places in this specification therefore do not necessarily refer * 1 to the same embodiment. In addition, the particular features, structures or features can be suitably combined in one or more embodiments, as will be apparent to a person skilled in the art from this description. Although some embodiments described herein include some, but not all, features included in other embodiments, combinations of features of different embodiments are intended to fall within the scope of the invention, and to form different embodiments, as will be apparent. with the craftsman. In the claims, for example, any of the described embodiments can be used in any combination.
    The term "gray value" as used here refers to a measurement of the intensity or intensity variation in an image. This intensity can be represented as a certain gray scale that goes from white to black, or a certain color tone, e.g. as in artificially colored images. Intensities can also be represented as a certain figure.
    The term "set" as used herein when referring to a set or set of calibration components includes two or more interconnected or connectable components.
    The term "opacity" as used herein refers to the measurement of the impermeability of an object or material for a certain type of radiation.
    "
    Although the term "radio opacity" refers in principle specifically to X-rays and similar radiation, it is also used interchangeably here with "opacity". The opacity depends on the frequency of the light in question. Opacity can be quantified in various ways, including the mass absorption coefficient or the absorption rate.
    The term "specific absorption rate" as used herein refers to a measurement of the extent to which energy is absorbed by an object or anatomical part when it is exposed to electromagnetic radiation, noise, particles or other energy or matter. It is defined as the current that is absorbed per mass and is expressed in watts per kilogram. The value of the specific absorption rate varies depending on the frequency of the electromagnetic radiation or noise, or on the type of particles or other energy or matter. Each time a specific absorption rate is mentioned in this text, the corresponding electromagnetic radiation, sound, particles or other energy or matter is the type of radiation, sound, particles or other energy or matter used in a medical imaging technique. In X-ray radiography for example, the electromagnetic radiation is the X-ray radiation in a certain frequency range.
    The term "damping coefficient" as used herein refers to an amount that indicates how easily a material or medium can be penetrated by a light beam, sound, particles or other energy or matter. A large damping coefficient means that the jet is quickly "damped" (weakened) as it passes through the medium, and a small damping coefficient means that the medium is relatively transparent to the jet. The damping coefficient is measured using units of mutual length. Each time a damping coefficient is mentioned in this text, the corresponding electromagnetic radiation, sound, particles or other energy or matter is the type of radiation, sound, particles or other energy or matter used in an imaging technique. For example, in X-ray radiography, the electromagnetic radiation is the X-ray radiation in a certain frequency range.
    Imaging techniques intended for the application of the present invention include techniques such as radiography, ultrasound, X-ray computed tomography (CT), thermography, magnetic resonance imaging (MRI), and nuclear medicine such as positron emission tomography (PET).
    t
    The term "medical imaging" as used herein refers to techniques and processes used to take images of the human or animal body (or parts and functions thereof), usually for clinical purposes (medical procedures for detecting, diagnosing or disease studies) or medical science (including the study of normal anatomy and physiology).
    The term "(medical) image" as used herein refers to an image that is obtained by a (medical) imaging technique. The term "image" further includes images obtained by radiography, ultrasound, CET, thermography, MR1 and nuclear medicine, including when used for non-medical purposes.
    In one aspect, calibration devices are provided for imaging. More specifically, calibration devices are provided that make it possible to obtain improved geometric accuracy and accuracy of the gray value of the images via X-rays, ultrasound, computed tomography (CT) with X-rays and / or magnetic resonance imaging (MRI), more in especially of a selected area of the body. In special embodiments, the calibration devices provided for imaging are radiographic calibration devices.
    A schematic illustration of an example of radiographic imaging is shown in Figure 1. An (X-ray) radiation source (7) produces an (X-ray) radiation beam (8). An area of interest (9), for example a body part, is placed between the radiation source and a detector (10). Since the beam is divergent, the image of the selected area on the detector is distorted. For example, the zones of the selected area near the edge of the radius are magnified more than the zones in the center of the radius. In addition, zones of the selected area closer to the detector are enlarged less than zones further away from the detector. Instability and inhomogeneity of the radiation source can cause even more distortions in the image. For quantitative measurements, the image must therefore be calibrated. The image is preferably calibrated based on a measurement of the errors (distortion) in different areas of the image.
    The calibration devices as described herein comprise a set of two or more, more particularly three or more, non-identical mutually connectable or mutually connected calibration components. More specifically, the calibration devices described herein include at least one set of two or more non-identical interconnected or connectable calibration components, wherein two or more non-identical interconnected or connectable calibration components have different radio opacity. The radio opacity of the calibration components is more particularly between, and not including, 0 and 1. The difference in radio opacity can be ensured in various ways, such as, but not limited to, optical density of the material, size etc. as will be described in detail below. The use of at least two calibration components with different radio opacity further improves the correction of the gray value.
    It is intended that the position of the calibration components, during the
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    use of the calibration devices is fixed with respect to each other. Accordingly, when the calibration components are provided as individual interconnectable components, the set comprises means or features for interconnecting the calibration components so that they form a fixed three-dimensional geometric figure. Various implementations of interconnecting calibration components are being considered. Thus, each calibration component in the set can be directly or indirectly connected to the other calibration components in. the series. For example, each calibration component can be directly connected to any other calibration component in the series. In particular embodiments, certain calibration components in the set are only connected to one other calibration component in that set. Some of the calibration components in the set may therefore be indirectly connected or connectable to each other. For example, in a set of three calibration components, the first component may be directly connected to the second component and the third component may also be directly connected to the second component, but not directly to the first component. In this embodiment, there is an indirect connection between the first and third component. In this way the number of connections is minimized and therefore the number of artifacts in the medical image due to the connections is reduced. All components can also be directly connected or connectable to each other.
    As indicated above, the calibration devices described herein may include one or more calibration components. The number of components I * depends to a certain extent on the applications of the calibration device. A set comprising 1 or 2 calibration components allows the calibration of the gray values in an image and allows the calculation of the degree of enlargement or reduction in the image (2-dimensional (2D) correction). At least 3 calibration components are required for a 3D geometric correction. In certain embodiments, the set of interconnected calibration components therefore comprises at least two, more in particular at least three, calibration components. The presence of four calibration components in an apparatus according to the present invention allows a correction of the gray value and georritic correction, and allows to evaluate the calibration of the medical imaging device. In particular embodiments, the set of interconnected calibration components thus comprises at least four calibration components. A set of five calibration components allows complete spatial, 3D and grayscale correction, without the need for further information about the calibration of the medical imaging device. In particular embodiments, the set of interconnected calibration components therefore comprises at least five calibration components. In addition to the above, it should be noted that the accuracy of the correction of spatial artifacts is further increased by the number of calibration components that are provided at different positions in the image. Furthermore, it is meant that in certain embodiments, sets of 6, 7, 8, 9, 10 or more calibration components are provided in the devices of the present invention.
    Within each set, the calibration components are provided so that they can be locked in one or more variable or fixed positions relative to each other. In particular embodiments, the calibration components, when interconnected, do not touch each other. In practice, overlaps of the calibration components in the image must be minimized and if possible avoided. It is preferred (but not necessary as described below) that the distance between the calibration components, or at least parts thereof, be at least 10 pixels on the medical image. Moreover, the size of the calibration components is preferably such that the size of each calibration component is different pixels in the image, preferably 10 or more pixels. The accuracy of the geometric correction and / or the correction of the gray value usually increases if the calibration components are spread over several pixels in the image.
    . }
    The nature of the connection between the calibration components is not critical. The calibration components can be connected, for example, by connecting elements such as, but not limited to, a straight or curved pin or rod.
    The connection of two or more of the calibration components in a set can additionally or also be achieved through direct contact between the calibration components. Direct contact between the calibration components is particularly useful when at least one of the calibration components is not rod-shaped.
    In particular embodiments, the sets of calibration components are provided as irreversibly fixed structures connected together, whereby connection can be ensured by any means such as gluing or production in one piece. In further embodiments, the calibration components are reversibly connectable and the set may include means or features to allow connection of the calibration components such that they are a fixed two-dimensional and more particularly. three-dimensional figure. In particular embodiments, it is preferable that the connection is stable and strong when the device is used and has no influence on the imaging of the calibration components. In special embodiments, the connection between the calibration components in the set is ensured by one or more special connection features and / or connection elements. In further particular embodiments, the connection may have a fixed relative position of the. ensure calibration components. The nature of the connection characteristic (s) and / or connection elements more particularly ensures that the calibration component can be placed at a distance from one or more other calibration components that is at least equal to the smallest diameter of the connection element.
    In special embodiments, the special connections and / or connecting elements ensure that one or more of the calibration components in the set can be connected to the other calibration components in different ways such that the relative position of the calibration components can be adjusted but then locked for use .
    Thus, the calibration components in the set have fixed relative positions, or can be interconnected to assume fixed relative positions. In particular embodiments, the set of interconnected calibration components is provided as a fixed set of calibration components. More specifically, the calibration device is provided and optionally made from a single piece.
    The calibration devices described herein may optionally include means for placing or positioning the one or more sets of calibration components on a body or body part. While "positioning" in this context implies the emphasis on the correct placement of the sets of calibration components, "placing" in this context refers more to the ability to maintain a fixed position on a selected object such as a body part. The means for placing or positioning the set of calibration components on a body or body part is more particularly a structure that is not part of the calibration components as such, but which can be (removably) attached thereto In particular embodiments, the means for facilitating the placement or positioning the positioning or placement of the set of calibration components on the body or on a body part such that the calibration components are located near a certain selected area on the body, optionally in a predefined position. In particular embodiments, the means is such that it allows for the placement of a plurality of calibration components near the selected area. In particular embodiments, the positioning and / or placement feature further ensures that the relative position of the set of calibration components relative to the selected area does not change during image taking. The selected region may be a bone, tissue, or tumor-known region, etc. Examples of positioning and / or placement features are described below.
    The relative position of two or more calibration components in a set can additionally or alternatively also be ensured by a housing. Such a housing is a structure that protects at least one of the calibration components and / or secures two or more of the calibration components relative to each other. Such a housing can further help to protect the shape and integrity of the calibration components, for example when they are made of brittle material. In these embodiments, the housing preferably covers at least a portion of the calibration component (s). In particular embodiments, the housing covers at least 30% of one or more of the calibration components. In particular embodiments, the housing covers at least 30% of the calibration component (s) on the surface of the calibration component (s) that form the outer surface of the set of calibration components. In particular embodiments, the housing consists of a single part, and may be connected to one or more of the (series of) calibration components via a snap-fit or clip-on mechanism. In other embodiments, the housing may comprise two or more removable connectable parts to more easily place and remove the set of calibration components in the housing. In special embodiments, the two or more parts of the housing can be removably connected via a snap-fit system.
    The housing is usually made of a material with a negligible damping coefficient and / or radio opacity, such that it has no influence on the image of the calibration components. Suitable materials include, but are not limited to,. polymers such as polystyrene, polyvinyl chloride, polyesters, polypropylene, polycarbonate, poly (methyl methacrylate), polyethylene terephthalate, polyamides or mixtures thereof. These materials have a low radio-opacity while still providing the necessary strength to hold the position of the calibration components. In special embodiments, each set of calibration components of the calibration device as described herein is provided with a separate housing. In other embodiments, two or more sets of calibration components of the calibration device may be in the same housing.
    The housing may further be suitable as a means for positioning and / or placing the set of calibration components on a selected object such as on the body. In special embodiments, the means for positioning and / or placement are thus integrated in a housing. However, the devices may also include special housing or positioning features. This will be further explained in the text.
    In certain embodiments, the calibration components in the set are connected in that they are embedded in a radiolucent material, i.e., a material with a radio opacity of 0, or close to 0.
    The shape and size of the calibration components of the calibration devices of the present invention is not critical. In certain embodiments, the calibration components are spheres, hemispheres, ellipsoids, cubes, tetrahedrons, pyramids, rods, disks, closures, wires or any combination thereof.
    In a particular embodiment, some of the calibration components are spheres. In certain embodiments, all calibration components are spherical, or substantially spherical. Bulbs are very stable to measure metrologically, are easily detected in an image by image processing software and are easy to produce accurately.
    In particular embodiments, one or more of the calibration components are rods. The rods are usually cylindrical and have an aspect ratio (i.e., length divided by width) between 2 and 10. In certain embodiments, all calibration components are rods.
    In certain embodiments, the calibration components comprise a combination of one or more spheres and one or more rods. The rods are not only intended as calibration components, but can further be used as connecting elements for connecting the spheres. In particular embodiments, one or more calibration components comprise a rod connected to a sphere.
    Each calibration component in a set can be identified in an image via unique features of that calibration component, or via its relative position relative to an identifiable calibration component. Consequently, most or all of the calibration components in a set are not identical, to ensure unambiguous identification of the calibration components in an image. The calibration components in an image can therefore have a different shape, size, inner diameter, outer diameter, marking, identification code, radio opacity or a combination thereof. These features will be described in more detail below.
    The identification of calibration components can be facilitated and improved if the calibration components are hollow. Thus, in particular embodiments, one or more of the calibration components in the set are hollow. In further particular embodiments, one calibration component in the set is solid, and one or more, more particularly all, other calibration components in the set are hollow. In other particular embodiments, all of the calibration components in the set are hollow. Calibration devices are more particularly provided wherein one or more of the calibration components in the set are hollow spheres. In further embodiments, one calibration component in the set is a solid sphere, and all other calibration components in the set are hollow spheres. In other particular embodiments, all of the calibration components in the set are hollow spheres. The ratio between the large and small radius, i.e. outer and inner radius, of a hollow sphere does not change on projection, which facilitates the identification of the calibration components in an image. In other embodiments, none of the calibration components are hollow.
    The identification of the calibration components in an image is also facilitated if the calibration components in the set have different (outer) diameters or sizes. Thus, in particular embodiments, the calibration components of one set have a different outer diameter or size. If the calibration device described herein comprises two or more rod-shaped calibration components, the rods may have a different width and / or length. In certain embodiments, the calibration device comprises two or more rod-shaped calibration components, which all have different widths.
    In particular embodiments of the calibration devices according to the invention, the (maximum) outer diameter of at least one calibration component is different from the outer diameter of another calibration component in the series.
    It should be noted that when calibration devices comprising "hollow calibration components" are meant, the ratio between the outer and inner diameter may vary. In particular embodiments, the ratio of the outer and inner diameter of at least one of the hollow calibration components is different from the ratio of the outer and inner diameter of another calibration component. In particular embodiments, each calibration component in the set of interconnected calibration components has an outer and inner diameter ratio that is different from the outer and inner diameter ratio of all other calibration components in the set or series. If each calibration component has a unique ratio of the inner and outer diameter, this facilitates the identification of the different calibration components in an image. In more particular embodiments of the devices of the present invention, the calibration components are hollow spheres, and the ratio between the inner and outer diameter is different for each sphere.
    The inner diameter of the calibration components that are hollow spheres or cylindrical rods is usually, for example, between 9.9 and 0.1 cm, preferably between 2.9 and 0.2 cm, more preferably between 0.9 and 0.2 cm and even more preferably between 0.6 and 0.3 cm. The outer diameter of the calibration components that are hollow spheres or cylindrical rods is usually between 10 and 0.4 cm, preferably between 3 and 0.4 cm, more preferably between 1 and 0.4 cm, and even more preferably i between 0.7 and 0.5 cm, provided that the outer diameter is larger than the inner diameter. The diameter of the calibration components that are solid spheres is usually between 10 and 0.1 cm, preferably between 3 and 0.3 cm, more preferably between 1 and 0.3 cm and even more preferably between 0.7 and 0.3 cm.
    In particular embodiments, the calibration components may additionally or also be identified in a different way, e.g., by marking the calibration component. The calibration components can be provided with an identification label or code that allows identification thereof in the image. Suitable methods for marking an object such that the marking is visible on the image taken depend on the nature of the imaging apparatus and are well known to those skilled in the art. The calibration components may additionally or also have a different size and / or shape.
    The intended use of the calibration apparatus and methods of the present invention is based in certain embodiments on providing the reference grayscale values of the image. Namely, in certain embodiments, the calibration devices of the present invention are used to calibrate gray levels in medical imaging. To this end, at least two of the calibration components must ensure the absorption of some, but not all, of the radiation used in medical imaging. This means that at least two of the calibration components present in a set of the device of the present invention must have a radio opacity between, and not including, 0 and 1. A material or object with a radio opacity of 0 allows a total transmission of the radiation used for medical imaging. A material or object with a radio opacity of 1 completely blocks the radiation used for medical imaging from the radiation source to the film or detector. If a calibration component has a radio opacity between 0 and 1, this means that the image of the calibration component will have gray values between the minimum and maximum gray values. Since radio opacity depends on the frequency used, the radio opacity of the calibration components is determined by its intended use. When the target is calibration of images made by X-rays, the radio opacity of the components must be between 0 and 1 for X-rays, etc. However, it is possible to provide an apparatus comprising at least one set of components, at least two of which of the calibration components present in the set have an opacity between 0 and 1 for the various intended imaging methods.
    Thus, in preferred embodiments, at least two of the calibration components of the calibration devices of the present invention have a radio-capacitance between 0 and 1. These calibration components are more particularly made of a material with a radio-opacity between, and not including of, 0 and 1. In more particular embodiments, all of the calibration components in the set have a radio opacity between 0 and 1.
    It is further noted that the quality of the correction will be improved when the opacity of the calibration components is in the range of the opacity values of the relevant region. In further particular embodiments, therefore, the radio opacity or the specific absorption rate (SAR) of each calibration component has a predetermined value, more particularly a value selected based on the opacity of the relevant region In order to ensure an optimal correction of the gray values, it is also important to provide calibration components with different opacity. In particular embodiments, the two or more calibration components within a set of the devices according to the invention have a radio opacity between 0 and 1, i.e. a radio opacity that is different from each other. In particular embodiments, all of the calibration components in a set have different radio opacity.
    When calibrating the gray levels of a selected area, it is particularly important to have references of gray levels that fall within the range between the minimum and maximum gray levels that are represented on the image of the relevant area. In particular embodiments, the resulting gray value of one calibration component in the set is lower than the average gray value of the relevant region of the body, while the resulting gray value of another calibration component in the set is higher than the average gray value of the relevant region. In particular embodiments, this means in practice that the SAR of one calibration component is lower than the average SAR in the relevant region and that the SAR of another calibration component is higher than the average SAR in the relevant region. In terms of radio opacity, this means in practice that the radio opacity on one calibration component is lower than the average radio opacity in the area concerned and that the radio opacity of another calibration component is higher than the average radio opacity. opacity in the relevant area.
    More specifically, it is considered that the resulting gray value of one calibration component, for a set of calibration components in the devices of the present invention, is equal to or lower than the lowest gray value of the respective region of the body, while the resulting gray value of another calibration component is equal to or higher than the highest gray value of the relevant area. In practice, this means that the SAR of one calibration component is equal to or lower than the lowest SAR in the relevant region and that the SAR of another calibration component is equal to or higher than the highest SAR in the relevant region. In terms of radio opacity, this means that the radio opacity on one calibration component is equal to or lower than the lowest radio opacity in the area in question and that the radio opacity of another calibration component is equal to or higher than the highest radio opacity in the area concerned.
    Those skilled in the art will appreciate that the radio-opacity and SAR of the calibration components and the relevant range, and the corresponding gray values, depend on the damping coefficient of the materials from which the calibration components are made and the relevant range. The radio opacity and SAR of a medium is specifically dependent on the attenuation coefficient of the materials from which that medium is made, and the amount of these materials present in that medium. The radio-opacity and SAR of the calibration components can thus be varied by varying the size of the calibration components, varying the ratio between the inner and outer diameter of the hollow calibration components, varying the materials from which the calibration components are made or any combination thereof. To identify the optimum materials, size and / or inner and outer diameter for the calibration components, the damping coefficients of possible materials from which the calibration components are made can be compared with the damping coefficients of the bone and tissues expected in the relevant area. Damping coefficients from a wide range of materials, fabrics, etc. are available in the literature (e.g. J.H. Hubbell and S.M. Seltzer, Tables or X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption
    Coefficients from 1 keV to 20 MeV for Elements Z = 1 to 92 and 48 Additional i
    Substances of Dosimetry Interest, National Institute of Standards and Technology, Gaithersburg, MD).
    Those skilled in the art will further know that the relationship between the attenuation of the radiation used in the medical imaging technique and the attenuation coefficient is given by Beer-Lambert's law.
    As explained above, the radio opacity of the calibration components of the devices of the present invention is at least partially determined by the material from which they are made. In particular embodiments, the calibration components are made from a single material. In further particular embodiments, the calibration components are made from a material comprising a polymer. Polymers can often be easily formed and / or sintered, which facilitates the production of the calibration components. To change the radio opacity of the calibration components, particles of different radio opacity can be added to the polymer. Thus, in particular embodiments, the calibration components are made from a polymer-containing particles. In further particular embodiments, the particles are made of a material with a higher attenuation coefficient than the polymer, preferably with a higher attenuation coefficient of the X-ray than the polymer.
    Suitable polymers include, but are not limited to, a natural or synthetic rubber or latex, polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamides, polyesters, aramides, polyethylene terephthalate, polymentyl methacrylate, polymethyl methacrylate or mixtures thereof. In particular embodiments, the polymer is a polyamide, e.g., nylon. In certain embodiments, the polymer is gutta percha. The particles may consist of a metal, metal oxide, metal sulfate or a compound comprising a metal. Suitable metals include, but are not limited to, barium, iron, lead, titanium, copper, platinum, silver, gold, nickel, zinc or alloys thereof. Particles may additionally or also consist of iodine or an iodine-containing compound. In particular embodiments, the calibration components and / or the connections between the calibration components consist of a polymer comprising barium sulfate particles. In special embodiments, the calibration components and / or the connections between the calibration components consist of a mixture of nylon (polyamide) with barium sulfate particles.
    The connections between the calibration components are preferably not visible on the medical image. Therefore, it is believed that when two or more calibration components are connected via connection elements, the connecting elements may consist of the same or different material from the calibration components. In particular embodiments, the connecting elements may consist of a material that gives a lower attenuation coefficient and / or radio opacity than the calibration components. In more particular embodiments, the connecting elements have a radio opacity of zero or nearly zero.
    For an optimal correction of the image, the various zones concerned in an image may require different specifications of the calibration components. In special embodiments, the specifications of the calibration components for specific zones concerned are listed, for example in a table. In further particular embodiments, the calibration components are selected, designed or produced on the basis of a list or table indicating which calibration devices are to be used for specific relevant zones, which may include different zones within an image.
    For example, as explained above, the required radio opacity of the calibration components or the optimum combination of calibration components may depend on the bone and tissues expected in the particular region. The damping coefficients of different tissue types and bones are well known, therefore it is possible to design and / or use calibration components for specific areas concerned, or even for specific areas in a relevant area. For example, it is possible to create a table that indicates the type of calibration component (shape, size, material, etc.) to be used for a specific area. The table or list may refer to a drawing of a (part of a) body, wherein different areas, or different areas within a certain area, are indicated, e.g. numbered.
    Thus, in certain embodiments, at least two of the calibration components in a set are adapted to a specific tissue type or region of the body. In further embodiments, all calibration components are adapted to a specific tissue type or region of the body.
    The production of calibration components and / or the production of a set of interconnected calibration components that form a single piece can take place in various ways. In certain embodiments, the set of calibration components according to the invention is made by Additive Manufacturing (AM) techniques. Additive Manufacturing (AM) can be defined as a group of techniques used to create a concrete model of an object usually using 3D computer aided design (CAD) data from the object. Various Additive Manufacturing techniques are currently available, including Stereolithography, Selective Laser Sintering, Fused Déposition Modeling, foil-based techniques, etc.
    In selective laser sintering, a powerful laser or other focused heat source is used for sintering or loading small particles of plastic, metal or ceramic powders into a mass that represents the 3D object to be formed.
    Fused deposition modeling and related techniques use a temporary transition from a solid material to a liquid state, usually due to heating. The material is pressed through an extrusion nozzle in a controlled manner and brought to the required location as described in, inter alia, U.S. Patent No. 5,141,680.
    Foil-based techniques attach coatings to each other by means of glue or photopolymerization and cut the object from these coatings or polymerize the object. Such a technique is described in U.S. Patent No. 5,192,539.
    AM techniques usually start from a digital representation of the 3D object to be formed. The digital representation is generally cut into a set of cross-sectional layers that can be superimposed to form the object as a whole. The AM device uses this data to build the object layer by layer. The cross-sectional data representing the layer data of the 3D object can be generated using a computer system and computer aided design and manufacturing (CAD / CAM) software.
    The dimensions and shape of the calibration devices as produced (e.g. via Additive Manufacturing) may differ slightly from the dimensions and shape of the calibration devices as designed. To correct for such manufacturing tolerances, information can be collected after production regarding the actual dimensions and shape of the equipment. In particular embodiments, one or more sets of calibration components of the calibration apparatus described herein are coupled to a (digital) identification after production. The identification may contain information about the shape and dimensions of the set (s) of calibration components and may be based on a (digital) scan of the device.
    This ensures that the images can be taken into account for the calibration of images. actual dimensions and shape of the calibration devices, which increases the reliability of the calibrated images.
    In the calibration devices of the present invention, the calibration components within a set are fixed or can be provided at different positions, which position (s) ensure that the absorption of the different calibration components generates optimum information for geometric and grayscale calibration. This is more particularly achieved by fixed positions which cause the lines connecting the centers of the calibration components (e.g. in the case of spherical, hemispherical, ellipsoidal, cubic, tetrahedral, pyramidal, disc-shaped and / or flat-ringed calibration components) and / or the longitudinal axis of the calibration components (e.g., in the case of the rod-shaped or filamentary calibration components) form a 3D structure.
    In special embodiments, the set of calibration components forms a polyhedron; Depending on the nature of the calibration components, this can be achieved in various ways. In particular embodiments, this is ensured by the fact that the centers of at least some of the calibration components form the vertices of an imaginary polyhedron (e.g., in the case of spherical, hemispherical, ellipsoidal, cube-shaped, tetrahedral, pyramidal, disc-shaped, and / or spheroidal) calibration components). Additionally or alternatively, the longitudinal axis of one or more calibration components may be positioned such that it forms the edge of an imaginary polyhedron (e.g., in the case of the rod-shaped or filamentary calibration components). In this context, usually only the outer calibration components are taken into account, since the set may comprise one or more calibration components that are located in the center of the imaginary polyhedron. Such a placement of the calibration components allows a stable ♦ calculation of the 3D position of the calibration components. In special embodiments, the set of calibration components forms an imaginary tetrahedron. In certain embodiments, at least one of the calibration components is within an imaginary polyhedron. In certain embodiments, one of the calibration components is in the center of the imaginary polyhedron. In certain embodiments, the calibration component that is located inside or the center of the imaginary polyhedron is solid, more particularly a solid sphere. The presence of an inner calibration component facilitates the determination of the spatial error in the image, and furthermore ensures that the set of interconnected calibration components forms a robust and compact structure. In certain embodiments, the calibration component in the center is a large sphere that is directly or indirectly connected to other calibration components such as smaller spheres and / or rods.
    In certain embodiments, each of the calibration components that form the imaginary polyhedron is directly connected to the calibration component that is located inside or the center of the imaginary polyhedron.
    The calibration devices described herein, including a set of calibration components, can be used for a complete geometric correction and correction of the gray values of an image. However, different areas in the image can exhibit different distortions. Therefore, an image correction based on the distortions in only one area of the image (i.e., the area in which the set of calibration components is located) can lead to incorrect corrections in certain other areas of the image. For an improved correction of certain areas in the image, it is therefore preferred that the calibration devices according to the present invention comprise more than one set of calibration components. Therefore, in certain embodiments, the medical imaging calibration apparatus of the present invention comprises more than one set of interconnected (or connectable) calibration components as described above. Some or all sets of interconnected calibration components can be identical to each other. In certain embodiments, the calibration device does not include identical sets of interconnected calibration components. In certain embodiments, one or each set of interconnected calibration components of the calibration device comprises a unique identifier for distinguishing that set from the other sets of the calibration device. A set or one or more of the calibration components can therefore, for example, be provided with an identification label or code that allows the identification of the set in the image.
    The calibration devices described herein include one or more sets of calibration components, which calibration components are placed at specific positions in the device such that, when the device is used, the components are in the vicinity of the relevant area. This more particularly ensures that the image taken from the relevant area comprises the image of the one or more sets of calibration components.
    In particular embodiments, the calibration devices of the present invention include, in addition to one or more sets of calibration devices, a means for placing and / or positioning the one or more sets of calibration components on a selected object such as a body or body part. This feature is usually not integrated in the calibration components, but is a separate feature. In special embodiments, the calibration device comprises more than one feature that can be used to position and / or place the one or more sets of calibration components on the relevant object.
    In particular embodiments, the feature suitable for positioning and / or placing the set or sets of interconnected calibration components is a feature that is hereinafter referred to as "placement means", such as a garment. In certain embodiments, the means for placement is an elastic garment, such as trousers or a sock.
    In certain embodiments, at least one set of calibration components of the calibration device described above is provided with a housing as described above, wherein said housing can be used as a means or feature for positioning. Namely, the housing may comprise, for example, a coupling surface suitable for the placement of the housing (holding a set of calibration components) on a body or body part. In particular embodiments, the coupling surface is specific to a patient, i.e. the coupling surface corresponds to at least a portion of the patient's anatomy that is a human or animal. This allows the calibration device to be placed on the anatomy of a body in a predefined way and therefore can increase the reliability of the corrected images of the patient's anatomy. The patient-specific coupling surface is usually designed based on a 3D model of a part of the patient's anatomy The model can be obtained on the basis of 2D or 3D images of the anatomy In special embodiments, the housing comprises one or more free-form structures that at least fit on a part of The term "freeform structure" as used herein refers to a structure with an irregular and / or asymmetrical flowing shape or circumference that more particularly fits at least a portion of the circumference of the anatomy, in special embodiments the free-form structure is therefore a free-form surface A free-form surface refers to a (substantially) 2D shape located in a 3D geometric space. Namely, as will be described below, such a surface can be considered as essentially 2D, but can have a varying thickness. The free form structure or surface is usually characterized by a lack of fixed radial dimensions, as opposed to regular surfaces such as surfaces, cylinders and conical surfaces. Freeform surfaces are well known to those skilled in the art and are commonly used in engineering design disciplines. Non-uniform rational B-spline (NURBS) math is commonly used to describe surface shapes; however, there are also other methods such as Gorden surfaces or Coons surfaces. The shape of the free-form surfaces is not characterized and defined in terms of polynomial equations, but by the poles, degree and number of patches (segments with spline curves). Freeform surfaces can also be defined as triangular surfaces, where triangles are used to approximate the 3D surface. Triangular surfaces are used in Standard Triangulation Language (STL) files that are well known to those skilled in CAD design. The free-form structures described herein are structured so as to fit specifically on the surface of the body parts, thereby giving the structures their free-form characteristics.
    The one or more positioning and / or placement means provided in the calibration apparatus described herein are thus typically provided separately or comprising one or more of the sets of calibration components attached thereto or contained therein. In particular embodiments, the one or more sets of calibration components may be fixed or may be attached to the positioning and / or placement means by means of a fastener. The fastener may be a lock that is present on the means for placement and / or the set of calibration components or parts thereof. The calibration components or the connecting elements may, for example, have holes in which pins fit on the means for placement. The sets may also be placed on the means for placement through a system of complementary forms. In particular embodiments, the calibration device is provided with means for placement that are a garment that is designed to include "openings" or "pockets" in which the sets of calibration components can be located. The sets of calibration components, or certain calibration components or compounds thereof, may additionally or also be sewn, stacked or glued on the means for placement.
    In special embodiments, the one or more sets of calibration components may be provided at predetermined and / or fixed positions on the relevant object. The ability to place the one or more sets of calibration components at a predefined position by means of positioning means (e.g., coupling surface of the housing) allows the calibration components to be placed on the body in a reproducible manner relative to the anatomy of the patient. The ability to attach the one or more sets of calibration components to a position by means of the placement means also ensures that they can be attached to the body for calibration components. Both aspects of positioning and placement can be provided by different characteristics, but they can also be combined into a single characteristic. For example, if the affected area is in the foot or leg of a patient, the means for placement may be a stocking to which the one or more sets of calibration components are or may be attached to specific locations such that the one or more sets of calibration components, with repeated placement of the stocking on the patient, each time placed in the same way in a position relative to the relevant area. The means for positioning and / or placement may be standard or specific to a patient. In particular embodiments, the positioning and / or placement means (e.g., such as the housing or the garment) may include one or more alignment features that can be used as a visual aid to ensure that the means for placement are always applied in the same way to the patient. However, given that the presence of the calibration components allows the calibration of the image regardless of its exact position, this means that the exact reproducibility of the position of the calibration component is not critical. However, it is important to ensure a maximum number of calibration components in the vicinity of the relevant area.
    In particular embodiments, the means for placement consist of a material with a low radio-opacity, preferably 0 or in the neighborhood of 0. Typical examples of materials that can be used for the means for placement include, in particular, garments, but they are not limited to, cotton, polyester, nylon, wool, silk, flax and combinations thereof. In its particular embodiments, the means for placement are made from an elastic material such as, but not limited to, a rubber, latex, elasticated cotton, Spandex ™, Lycra ™, or nylon.
    In a further aspect, the use of two or more non-specific geometric objects with a radio opacity between 0 and 1 is provided for the correction of the gray value of a medical image. In further embodiments, the use is provided with three or more non-identical geometric objects with a fixed relative position, wherein at least two of said calibration components have a radio opacity between 0 and 1, for the geometric correction and the correction of the gray values of a medical image, for example for images obtained by radiography, ultrasound, CT, thermography, MRI or PET. The geometric objects are preferably calibration components as described herein, the calibration components being more particularly part of a calibration device as described here.
    A further aspect provides methods for acquiring and correcting images of an object, such as medical images. Methods for image correction and / or calibration are more particularly provided, comprising the following steps: i) providing an image wherein said image, in addition to the image of the object, is also an image of one or more sets of two or comprises several non-identical and interconnected or connectable calibration components; and ii) correcting the image of the object based on the information obtained from the measurement of the geometry and gray values of said image of said calibration components.
    In particular embodiments, the object is a part of the body or a region thereof. In particular embodiments, methods are provided for making medical images comprising the following steps: (I) applying the non-identical geometric objects or a calibration device for medical imaging as described above to the patient in the relevant area; and (II) the acquisition of a medical image of the relevant area.
    The images obtained by these methods can be corrected for the spatial positioning of the area in question, the gray values, etc. This enables a more accurate evaluation of the area in question and further enables a more accurate comparison of images taken on at different times, or even from different patients or different areas. Therefore, in a further aspect, methods are provided for the calibration and / or correction of images such as medical images. Namely, the methods and instruments described herein permit the calibration of medical images so that certain features can be compared on different images. Methods for correcting a medical image for improving its geometric accuracy and / or the accuracy of the gray value are more particularly provided. Based on this, different images can be compared based on geometric data (e.g., reflective size, shape) and / or gray values (e.g., reflecting the density) of features. In particular embodiments, the present invention provides methods for the correction of radiographic images.
    In particular embodiments, the methods for taking and / or correcting medical images are non-invasive for the human or animal body.
    In particular embodiments, it may be interesting to compare different images of the same anatomical feature for the same patient that were taken at different times. Additionally or alternatively, it may also be interesting to compare different images of the same anatomical feature in different patients. Further applications will be apparent to those skilled in the art. The methods according to this aspect of the invention usually include an image correction. The correction can be performed "live" or "in line".
    The methods for correction and / or calibration of (medical) images by calibration according to the present invention usually require one or more of the following input data, which can be determined offline.
    a) The relative fixed position of the various geometric objects or calibration components. These are the relative positions of the geometric objects or calibration components in each set.
    b) The relative variable position of the geometric objects or calibration components. This is the position of the sets of geometric objects or interconnected calibration components relative to each other and to the patient's anatomy. This relative position is variable, since certain deviations from the average relative position can occur each time an image is taken, for example due to changes in the patient's anatomy.
    c) The shape parameters of the geometric objects or calibration components. This includes the shape, inner and outer dimensions, etc. For a geometric object or calibration component that is a hollow sphere, the parameters include the outer diameter, the inner diameter, and the information that the geometric objects or calibration components are spherical.
    d) Specific absorption rate of the geometric objects or calibration components. The damping coefficient of the material or materials from which the calibration components are made can also be given as input data. The specific absorption rate of the geometric objects or calibration components can be calculated using the damping coefficients and the shape parameters described above.
    The methods of the present invention include applying the geometric objects or devices of the present invention comprising calibration components in the vicinity of the relevant body part, in a particular position, each time a medical image is taken. Although not critical, the medical imaging calibration apparatus of the invention can further facilitate the repeated positioning of the calibration components at the same position on the body.
    In particular embodiments, the method for image correction according to the present invention comprises the following steps: (I) providing an image of the relevant area, said image being an image of one or more sets of two or more non-identical geometric objects or includes non-identical and interconnected or connectable calibration components; and (II) correcting the image based on the information obtained from the measurement of the image of the geometric objects or calibration components.
    The methods of the present invention are thus based on images obtained from a patient in which the geometric objects or the calibration device are located near the relevant area. In a special embodiment, step (I) comprises providing an image, wherein said image comprises an image of one or more sets of geometric objects or calibration components.
    In further particular embodiments of the invention, the methods further include obtaining the images. More specifically, the methods include the following step: (I) applying the medical imaging calibration apparatus as described herein to the patient in the particular area; and (II) the acquisition of a medical image of the relevant area; and (III) the correction of the medical image based on the information obtained from the calibration components.
    In particular embodiments, methods are provided for the correction and / or calibration of images, preferably with the aid of the calibration devices described. When use is made of the calibration devices such as the devices described herein, images are obtained which can be corrected whenever this is deemed necessary.
    In particular embodiments of the methods for correction and / or calibration described herein, the correction comprises a correction of the gray value of the image. Namely, the image of the calibration components or geometric objects 1 'can be used to correct the gray value of the relevant area. The calibration components or geometric objects have a known absorption rate and the theoretical gray values can be calculated. These can then be compared with the measured gray values to determine the error. The gray value can then be corrected for the x-ray radiation by applying the error to the x-ray radiation. In special embodiments, this is performed with the help of an error correction table, which gives the errors for different areas in the image.
    The methods of correction according to the present invention additionally or also include a geometric correction of the image. Geometric accuracy is a common problem with dimensional metrology. Due to various mechanical and optical effects, the image can be distorted. Geometric correction is based on the 3D position of the various components or geometric objects. This may include determining the 2D positions of each component or object of a set, and, based on the known shape of the component, deriving the 3D positions. However, when the components or objects have known fixed relative positions, the possible positions can be calculated and compared with the obtained image. Comparison of the known relative positions of the components or objects with the measured position gives the geometric error. The error can be re-applied to the image using an error table.
    In particular embodiments, the methods described comprise a combination of a gray value correction and geometric correction of the image.
    The correction of the medical image may additionally or also include centering of the patient. To this end, different sets of calibration components or geometric objects are used that are provided at fixed positions in the device. The information about the calibration components or geometric objects can provide information about the position and / or (part of) the shape of the patient, or a body part of the patient (i.e. the area concerned).
    In certain embodiments, the methods for correcting and / or calibrating an image include the following step: (I) applying three or more non-identical geometric objects as described herein to the patient in the particular area; (II) acquiring a medical image of the relevant area; and (III) applying the gray value correction and geometric correction to the medical image based on information obtained from the geometric objects.
    In particular embodiments, the methods for correcting the calibration of medical images described herein include one or more or all of the following steps: (i) Applying the geometric objects or the calibration apparatus for medical imaging as described above to the patient on the relevant area. In particular embodiments, the patient wears a garment with one or more sets of interconnected calibration components or one or more enclosures comprising the calibration components are placed on the patient so that the sets of interconnected calibration components are located near the relevant region and in the field of view of the imaging technique. In further embodiments, the garment or the housing (s) contain different sets of calibration components. This is a. reliable correction in different areas of the image possible.
    (ii) Acquisition of a medical image of the relevant area. Before starting step (ii), step (i) must be completed. In addition to the relevant area, at least one, and preferably all, sets of geometric objects or interconnected calibration components must be visible on the medical image. More than one image can be taken during this step.
    It can also be considered that the methods of the present invention comprise only one correction step, starting from the images obtained as described above in steps (i) and (ii).
    (iii) Identification of the geometric object or calibration components in the medical image, i.e. the medical image or images obtained in step (ii). If the geometric objects or calibration components differ from each other within a set, identification of the different objects or components will be required to apply calibration. leave. In particular embodiments, at least two geometric objects or calibration components were identified for the correction of the gray value. Similarly, in certain geometric correction embodiments, at least three geometric objects or calibration components must be identified in a set. All geometric objects or calibration components in one set are preferably identified. If it is interesting, all calibration components of all sets are identified. This step can be automated using a computer. This step may, for example, include a search for (images of) hollow spheres, i.e. the geometric objects or calibration components, or the medical image. The 2D position of each sphere on the image is thereby determined. Each geometric object or calibration component is then identified, for example via the ratio of the outer and inner radius of the spheres. In particular embodiments, the components are tagged or labeled to allow immediate identification in the image.
    (iv) Determination of the 3D position of each geometric object "or calibration component. This step is optional. In particular embodiments, the calibration components in each set have fixed known relative positions. For example, each set may consist of four hollow spheres forming a tetrahedron with a hollow or solid sphere in the center of the tetrahedron, each possible position of a tetrahedron corresponds to a different projected silhouette on the medical image, so that every possible position of the calibration components can be identified based on the image.
    As defined above, depending on the nature of the intended correction, the methods may include one or more of the following steps: 1. Calculation of the geometric error on the image. The geometric error can be determined based on the information obtained in step (iv), the position of the central calibration component in each set and the 2D position of the central calibration component on the medical image. A more accurate calculation of the geometric error is obtained with the help of multiple sets of calibration components.
    2. Geometric correction of the medical image. In particular embodiments, an error table is made based on the geometric error calculated in step (v), and this error table is applied to the image.
    3. Correction of the position of the set of geometric objects or calibration components. In special embodiments, the positions of the set or sets of calibration components are corrected based on the error tab! which is prepared in step 2.
    4. Determining the position and certain shape parameters of the patient. The positions of the geometric objects or calibration components are known from the previous steps. The means for placing the set or sets of geometric objects or calibration components on the body are designed such that they always place the set or sets of calibration components in the same way with respect to the patient's anatomy. The position of the patient can then be obtained based on the medical image. Although the relative positions of the calibration components may deviate to some extent, the deviations calculate the average when optimizing the recording. The deviation from the average is indicated as basic information about the anatomy and therefore information about some form parameters of the patient.
    5. Calculation of the greyscale errors in the image. The specific absorption rate of the geometric objects or calibration components is known and is part of the input, so for all geometric objects or calibration components that are not impeded by the anatomy of the patient, the theoretical gray values can be determined. The differences with the measured gray values are then the errors.
    6. Correction of the gray levels on the medical image. In particular embodiments, an error table is prepared based on the gray value error calculated in step 5, and this error table is applied to the image. This error table is preferably a set of local tables of gray value errors that can be interpolated in the space. Different local tables of grayscale errors can be obtained by placing a set of calibration components in different zones in the image.
    In particular embodiments, the methods for correcting medical images as described herein further include the step of removing the geometric objects or calibration components for medical imaging from the medical image. Since the position of the calibration components is known and also its effect on the medical image is known via its known specific absorption rate, the effect of the calibration components can be removed! 'from the medical picture. This results in a medical image that no longer exhibits artifacts due to the calibration components.
    Figure 5 shows a flow chart of exemplary steps in a method for correction of medical images according to the present invention. The diagram shows possible steps of the method (full line rectangles and arrows), together with the input and output for each step (parallelogram one and arrows in dotted line).
    The calibration devices and methods of the present invention can be used to calibrate images obtained by X-ray radiography, ultrasonography, MRI or CT. A further aspect of the present invention therefore provides for the use of the medical imaging calibration apparatus as described above, for the quantitative measurement of data obtained by X-ray, ultrasonography, MRI or CT radiography.
    In a further aspect, computer program products are provided for performing geometric correction and / or correction of the gray values on images obtained by medical imaging, as described above, comprising: • a computer readable medium; and • software instructions, on the computer-readable medium, for enabling the computer to perform some or all of the following operations: - Identification of the calibration components (or geometric objects) in a medical image; - Calculation of the geometric error on the medical image based on the image of the calibration components (or geometric objects) and geometric correction of the medical image; - Correction of the positions of the set of calibration components (or geometric objects).
    - Determining the position and shape parameters of the patient, based on the image of the calibration components (or geometric objects); - Calculation of the greyscale value on the medical image based on the image of the calibration components (or geometric objects) and correction of the gray values of the medical image; . * - Removing the artifacts from the calibration of the medical imaging from the medical image.
    The present invention will be illustrated by the following non-limitative embodiments.
    EXAMPLES
    Example 1 - Development and use of the calibration device a) Development of the calibration device
    The calibration device (1) comprises different sets (2) of calibration components, as shown in Figure 2.
    An example of a set (2) according to a particular embodiment of the present invention is shown in Figure 3. The set (2) consists of five calibration components (4, 5) which can be solid spheres with varying diameters, and / or hollow spheres with varying ratios between the large and the small radius (not shown). The varying diameters and / or ratios facilitate the identification of the bulbs. Moreover, the difference in overall diameter and / or thickness of the sleeve causes differences in absorption speed between the spheres. The outer calibration components (4) are interconnected such that the lines connecting the centers form the edges of a tetrahedron, with one calibration component (5) in the center. Thus, there are four outer calibration components (4) and an inner calibration component (5). All outer calibration components are directly connected to the inner calibration component via connections (6).
    An example of a set (2) according to another embodiment of the present invention is shown in Figure 4. The set (2) consists of six calibration components (4, 5) which can be hollow or solid spheres, tetrahedrons or pyramids. The tetrahedrons and pyramids can be regular or irregular. The outer calibration components (4) are interconnected such that the lines connecting the centers form a pyramid, with one calibration component (5) in the center. There are therefore five outer calibration components (4) and one inner calibration component (5). All outer calibration components are directly connected to the inner calibration component via connections (6).
    ï
    As shown in Figure 2, the calibration device (1) further comprises means (3) for placing the set (s) of calibration components. The means (3) for placement is a garment that is designed so that it always positions the sets of calibration components in the same way with respect to the patient's anatomy. In addition, the sets of calibration components are located near or on the respective area, and at different locations on the stocking, in such a way that the different areas in the image each contain one or more sets of calibration components.
    b) Applying the device and scanning the patient
    The stocking comprising the sets of calibration components is applied to the patient at a specific position and one or more X-rays are taken.
    c) Identification of the components of the stocking
    A computer program is used to identify the hollow spheres (based on the ratio of the inner / outer radius) and to determine the position of the spheres in the 2D image.
    d) Determination of the 3D position of each component
    It is theoretically possible to determine the 3D position of a sphere based on the 2D position and shape parameters of its projected silhouette. The projected silhouette of a hollow sphere is 2 "concentric" ellipses. The eccentricity of the two ellipses indicates the (projective) distance of the perpendicular projection axes.
    . The ratios between the measured (small) rays and the known 3D rays gives the Z position of the sphere (the scale factor).
    However, a more metrologically stable solution is used since the spheres in the sets have a fixed known relative position, which forms a tetrahedron and a hollow sphere in the center of the tetrahedron. Every possible position of a tetrahedron corresponds to a different projected silhouette and can therefore be identified on the X-ray image.
    e) Calculation of the geometric error on the X-ray image
    After having used the 4 outer spheres to identify the 3D position of each set of calibration components and based on the nominal position of the middle sphere we compare it with the measured position thereof, which gives us the local error. Since the calibration device comprises more than one set of calibration components, more than one local error can be calculated. The local errors can then be interpolated into the room.
    f) Geometric correction of the X-rays
    This is a standard procedure. An error table is drawn up and this is simply applied to the X-rays. The positions of the sets of calibration components are corrected based on the error table.
    g) Determining the position and (part of) the patient's shape parameters
    The stocking can now also be used to determine the centering of the patient. We have calculated the different positions of the bulb groups. These groups are attached to the stocking. Since the stocking is designed so that it always positions the bulb groups in the same way with respect to the patient's anatomy, deviations in the position of the bulbs are indicative of changes in the patient's anatomy. There will of course be abnormalities because the patient is different. However, if an optimization on the registration is used, the average of these differences is calculated. The variation from the average provides the basic information about the patient's anatomy. This information also makes. part of the output.
    h) Calculation of the gray level error and correction of the gray level on the X-ray image
    The hollow spheres are now used to calculate the gray value error. We know what the absorption rate must be and it can be measured. The theoretical gray levels can be calculated for all spheres that are not obstructed by the patient. The differences with the measured gray values are the errors. The. correction of the gray value of the X-ray image is carried out by applying an error correction table. This image correction table is a set of local gray value error tables that can be interpolated in the room.
    Example 2 - Special embodiments of interconnected calibration components
    Figure 6 (A-D) shows a set (2) of interconnected calibration components (4, 5) according to a particular embodiment of the present invention. The set includes one spherical calibration component (4) connected to three calibration components (4 "), each consisting of a solid cylindrical rod and sphere. The rods form the edges of a tetrahedron, while the spheres form the vertices of the tetrahedron. The combination of the spheres and rods allows a complete 3D geometric correction and correction of the gray values of a medical image, such as a radiographic image. The spheres are identical, but can be identified in an X-ray because each of the rods of the calibration components has a unique width.
    The relative position of the bulbs is determined via the rods and further secured via a housing (11) in which the bulbs are located. The housing also encapsulates the spheres, protecting its structural integrity. The housing consists of two parts that can be detached from each other, so that the set (2) can be easily inserted into the housing and removed easily. The housing is made of a material with a low radio opacity, such as a polymer. The housing further comprises a coupling surface (12) specific to the patient for positioning the housing on the body part of a patient. This ensures accurate positioning of the calibration components on the body part.
    Figure 7 (A-D) shows a similar set (2) of interconnected calibration components (4, 5) as shown in Figure 6, in other housing (11). The housing (11) has a triangular shape and clips onto the two longest bars of the calibration components, thereby securing their relative positions. The stiffness and strength of the shortest rod is sufficient as such and requires no further support from the housing. The housing further comprises a coupling surface (12) for positioning the housing on the body part of a patient.
    Figure 8 (A-D) shows a similar set (2) of interconnected calibration components (4, 5) as shown in Figure 6, in other housing (11). The housing (11) comprises four hollow hemispheres and is designed to clip onto one of the spheres of the calibration device while holding the other three to ensure its relative positions.
    Example 3 - Special embodiments of interconnected calibration components
    Figures 9 A and B illustrate a configuration of three sets (2) of interconnected calibration components (4, 5) according to a particular embodiment of the present invention. Each set (2) comprises a spherical calibration component (4) and three rod-shaped calibration components (5). The rods form the edges of a tetrahedron, while the sphere forms a vertex of the tetrahedron.
    The spherical calibration components of the three sets have a different diameter, which simplifies the identification of the sets. Moreover, the different diameters of the spheres lead to a different radio opacity for each sphere. The rod-shaped calibration components of each set differ from each other. More in particular, the rods have a different diameter and / or length. Each rod in a set is perpendicular to the other rods in the set. This simplifies the image correction.
    To further simplify the image correction, the sets (2) can be arranged such that two or more rods of the different sets are parallel to each other. The sets can further be arranged in a specific way relative to one or more calibration components (4 ') that may or may not belong to a set of interconnected calibration components.
    Example 4 - Special embodiments of interconnected calibration components
    Figure 10 (A-C) shows a set (2) of interconnected calibration components (4, 5) according to a particular embodiment of the present invention. The set includes five spherical calibration components (4, 5). The centers of the outer spherical calibration components (5) form the vertices of a tetrahedron. The outer calibration components (5) are connected to the inner spherical calibration component (4) via rod-shaped connecting elements (6). The rods (6) can also be used as calibration components.
    The spherical calibration components (4, 5) have a different diameter and radio opacity. The spheres (and optionally the rods) allow a full 3D geometric and gray value correction of a medical image such as a radiographic image.
    The relative position of the spheres is fixed by means of the rods and is further ensured by a housing (11) that is clicked onto the rods (6). The housing can protect the set of interconnected calibration components during transport. Additionally or alternatively, the housing may be made of a radiolucent material and may be used to protect the set during the acquisition of a medical image. The housing may include a cover (13) to further protect the set (2).
    权利要求:
    Claims (25)
    [1]
    A method for image correction, comprising the steps of: i) providing an image wherein said image comprises an image of one or more sets of three or more non-identical and interconnected calibration components configured to have a fixed three to form a dimensional geometric figure, wherein said calibration components differ at least in radio opacity; and ii) correcting the geometry and gray values of the image based on the information obtained from the measurement of the geometry and gray values of said image of said calibration components.
    [2]
    Method according to claim 1, which comprises the following: - the identification of two or more calibration components in the image; - the determination of the location and gray value of said two or more components in the image; - the calculation of the gray value error based on the difference between the determined gray value and the calculated gray value; and - the application of said correction to said image.
    [3]
    Method according to claim 1 or 2, wherein step i) comprises providing an image, wherein said image comprises an image of one or more sets of three or more non-identical calibration components, wherein said three or more non-identical calibration components least differences in radio opacity and are interconnected so that they form a fixed three-dimensional geometric figure.
    [4]
    Method according to any of claims 1 to 3, which comprises: - the identification of at least three calibration components in the image; - the determination of the three-dimensional position of each calibration component; - the calculation of the geometric error on the image; and - the application of said correction to said image.
    [5]
    The method of any one of claims 1 to 4, wherein said image comprises an image of at least a portion of a patient and wherein said correction comprises providing information about the position and shape of said portion of said patient.
    [6]
    The method of any one of claims 1 to 5, wherein said correction is further based on the determination of errors in more than one area in the image.
    [7]
    The method of any one of claims 1 to 6, wherein said correction is an in-line correction.
    [8]
    A medical imaging calibration apparatus comprising three or more non-identical and interconnected calibration components, wherein at least two of said calibration components have a different radio opacity that is between, not including, 0 and 1, and wherein said calibration components are configured to form a fixed three-dimensional geometric figure.
    [9]
    The medical imaging calibration apparatus of claim 8, further comprising a separate feature for positioning and / or placing said set of calibration components on the body.
    [10]
    The medical imaging calibration apparatus according to claim 8 or 9, wherein said interconnected calibration components have fixed relative positions.
    [11]
    A medical imaging calibration apparatus according to any of claims 8 to 10, wherein said calibration components comprise one or more elements selected from spheres and rods.
    [12]
    A medical imaging calibration apparatus according to any one of claims 8 to 11, wherein the centers or longitudinal axes of said interconnected calibration components form respective vertices of an imaginary polyhedron.
    [13]
    The medical imaging calibration apparatus of claim 12, wherein said set of interconnected calibration components forms a tetrahedron.
    [14]
    A medical imaging calibration apparatus according to claim 12 or 13, wherein said set of interconnected calibration components forms a polyhedron with at least one calibration component disposed within the polyhedron.
    [15]
    A medical imaging calibration device according to any of claims 8 to 14, wherein at least one of said calibration components is hollow.
    [16]
    A medical imaging calibration device according to any of claims 8 to 15, further comprising a housing for holding two or more of said calibration components.
    [17]
    The medical imaging calibration apparatus of claim 16, wherein said housing comprises a coupling surface specific to the patient for positioning said housing on the body.
    [18]
    A medical imaging calibration apparatus according to any of claims 8 to 17, wherein the outer diameter of at least one of said calibration components is different from the outer diameter of another calibration component.
    [19]
    A medical imaging calibration device according to any of claims 8 to 18, comprising at least two sets of calibration components.
    [20]
    A medical imaging calibration device according to any of claims 8 to 19, wherein said special feature for positioning and / or placing said set of calibration components is a garment.
    [21]
    A medical imaging calibration apparatus according to any of claims 8 to 20, wherein said calibration components are adapted to a specific type of tissue or bone or a specific area of the body.
    [22]
    A medical imaging calibration apparatus comprising at least five non-identical spheres having an X-ray opacity that is between, and not including, 0 and 1, said spheres being or being interconnected in such a way that the centers of at least four of said spheres form the angular points of an imaginary polyhedron, and one sphere is located within the polyhedron.
    [23]
    Use of a medical imaging calibration device according to any of claims 8 to 22 for quantitative measurement on data obtained by X-rays, ultrasound, CT and MRI.
    [24]
    24. Use of three or more non-identical geometric objects with a fixed relative position, wherein at least two of said geometric objects have a different radio opacity between 0 and 1, and wherein said geometric objects have a three-dimensional geometric figure forms, for a geometric correction and correction of the gray values of an image obtained by a medical imaging method.
    [25]
    The use of claim 24, wherein said geometric objects are selected from spheres and rods.
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    同族专利:
    公开号 | 公开日
    CN103596501A|2014-02-19|
    US20140056495A1|2014-02-27|
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    GB201107385D0|2011-06-15|
    JP2014512920A|2014-05-29|
    EP2704635A1|2014-03-12|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US6005907A|1996-05-17|1999-12-21|Sirona Dental Systems Gmbh & Co. Kg|Method and apparatus for producing tomosynthesis exposures employing a reference object composed of a number of sub-objects|
    EP0874536A1|1997-03-31|1998-10-28|General Electric Company|Apparatus and method for automatic monitoring and assessment of image quality in X-ray systems|
    DE19802414A1|1998-01-23|1999-07-29|Merck Patent Gmbh|Component for more accurate semi-quantitative density determination of bones, bone replacement materials or bone implants|
    US6454460B1|1998-09-08|2002-09-24|Naganathasastrigal Ramanathan|System and method for evaluating and calibrating a radiation generator|
    DE19956636A1|1999-05-31|2000-10-19|Herzog Rainer|Automatic bone density and structure determination, for orthodontic application, by use of reference object for determination of gradients and texture by comparison with test structure|
    US6292535B1|1999-12-21|2001-09-18|Canon Kabushiki Kaisha|Digital X-ray imaging system with automatic display image greyscale enhancement and method|
    DE10114317A1|2000-03-31|2001-11-08|Ge Med Sys Global Tech Co Llc|Material scouring evaluation method e.g. for calcium scouring, involves performing material scouring based on phantom image, and comparing material scouring result with estimated phantom image result|
    DE20009714U1|2000-05-30|2001-10-11|Pandikow Bjoern|Phantom body of a balancing device of a radiation planning system|
    US20020015476A1|2000-07-25|2002-02-07|Siemens Aktiengesellschaft|X-ray computed tomography apparatus|
    US20030072409A1|2001-10-12|2003-04-17|Kaufhold John Patrick|Methods and apparatus for estimating a material composition of an imaged object|
    WO2006133574A1|2005-06-17|2006-12-21|Volumetrics Medical Corp.|Method of evaluating the resolution of a volumetric imaging system and image phantom used during resolution evaluation|
    WO2009060346A2|2007-11-06|2009-05-14|Koninklijke Philips Electronics N.V.|System for quantification of neovasculature in ct volumes|
    EP2156790A1|2008-08-22|2010-02-24|BrainLAB AG|Allocation of x-ray markers to picture markers depicted in an x-ray picture|
    US4663772A|1985-09-30|1987-05-05|Picker International, Inc.|Bone mineral analysis phantom|
    US5141680A|1988-04-18|1992-08-25|3D Systems, Inc.|Thermal stereolighography|
    US5192539A|1988-07-21|1993-03-09|Akzo N.V.|Infectious bursal disease virus production in continuous cell lines|
    US5651046A|1995-06-22|1997-07-22|Duke University|Anatomic phantom for evaluation of projection radiographic imaging systems|
    US5771895A|1996-02-12|1998-06-30|Slager; Cornelis J.|Catheter for obtaining three-dimensional reconstruction of a vascular lumen and wall|
    US6010445A|1997-09-11|2000-01-04|Implant Sciences Corporation|Radioactive medical device and process|
    US5951475A|1997-09-25|1999-09-14|International Business Machines Corporation|Methods and apparatus for registering CT-scan data to multiple fluoroscopic images|
    WO1999039765A2|1998-02-10|1999-08-12|Implant Sciences Corporation|Soft x-ray emitting medical devices|
    AU3889500A|1999-03-18|2000-10-16|Eisenlohr Technologies, Inc.|Radiographic reference marker|
    KR20040051938A|2002-12-13|2004-06-19|한국전자통신연구원|Method for calibrating bone mineral density index variation and storage medium for storing program of executing the same|
    US6979124B2|2003-02-11|2005-12-27|General Electric Company|Image quality vascular uniformity evaluation method and apparatus|
    JP2005095478A|2003-09-26|2005-04-14|Sanyo Electric Co Ltd|Apparatus, method, and program for medical image processing|
    US7480363B2|2004-09-15|2009-01-20|Ge Betz, Inc.|Converting a digital radiograph to an absolute thickness map|
    US8048141B2|2004-12-07|2011-11-01|Boston Scientific Scimed, Inc.|Medical device that signals lumen loss|
    US20080081980A1|2006-09-18|2008-04-03|Michael Maschke|Apparatus and process for stroke examination and treatment using a C-arch X-ray system|
    JP5068979B2|2006-11-07|2012-11-07|日揮触媒化成株式会社|Dental filler, method for producing the same, and dental composite material|
    US7835559B1|2007-04-27|2010-11-16|The Board Of Trustees Of The Leland Stanford Junior University|Method and apparatus for quantitative and comparative analysis of image intensities in radiographs|
    US20080273665A1|2007-05-04|2008-11-06|Michael Rolle|Adjustable Radiographic Marker and Calibration Aid|
    WO2008146069A1|2007-05-25|2008-12-04|Ecole Nationale Superieure D'arts Et Metiers |Method for reconstruction of a three-dimensional model of a body structure|
    US20090292309A1|2008-05-20|2009-11-26|Michael Maschke|System and workflow for diagnosing and treating septum defects|
    US8471222B2|2009-11-18|2013-06-25|Mitsubishi Heavy Industries, Ltd.|Radiotherapy apparatus control method and radiotherapy apparatus control apparatus|
    GB201002855D0|2010-02-19|2010-04-07|Materialise Dental Nv|Method and system for achiving subject-specific, three-dimensional information about the geometry of part of the body|
    BE1019572A5|2010-11-10|2012-08-07|Materialise Nv|OPTIMIZED METHODS FOR THE PRODUCTION OF PATIENT-SPECIFIC MEDICAL TOOLS.|
    US8894280B2|2011-12-31|2014-11-25|Carestream Health, Inc.|Calibration and correction procedures for digital radiography detectors supporting multiple capture modes, methods and systems for same|CN104271076B|2011-12-23|2017-05-31|物化股份有限公司|Service precision maps with stability analysis to design the system and method with generating device|
    EP2660776A1|2012-05-01|2013-11-06|Universität Bern|Image distortion correction and robust phantom detection|
    US9055915B2|2012-07-10|2015-06-16|Ghansham D. Agarwal|Device for externally marking the location of organs on skin during a cat scan|
    US20140064442A1|2012-08-31|2014-03-06|Ghansham Das AGARWAL|Novel device for marking location of organs on skin as per cat scan|
    US10943366B2|2012-10-09|2021-03-09|Pixameter Corp.|Wound characterization of a patient|
    US9410827B2|2012-10-09|2016-08-09|Pixameter Corp.|Measurement using a calibration pattern|
    EP2737852B1|2012-11-30|2015-08-19|GE Sensing & Inspection Technologies GmbH|Method for detecting the geometric imaging properties of a flat screen detector, accordingly designed x-ray test system and calibration body|
    GB2519586B|2013-10-28|2015-12-02|Elekta ltd|Phantoms and associated methods for calibrating imaging systems|
    GB2542518B|2014-05-21|2020-07-22|Tangible Play Inc|Virtualization of tangible interface objects|
    US9750479B2|2014-06-27|2017-09-05|Hexagon Metrology, Inc.|Three-dimensional x-ray CT calibration and verification apparatus and method|
    WO2016149757A1|2015-03-23|2016-09-29|Straxcorp Pty Ltd|Automated identification and selection of a region of interest in imaging|
    EP3365664A1|2015-10-23|2018-08-29|Hexagon Metrology, Inc|Three-dimensional computed tomography gauge|
    WO2017205505A1|2016-05-24|2017-11-30|Hexagon Metrology, Inc.|X-ray computed tomography gauge|
    CH712867A1|2016-08-30|2018-03-15|Medivation Ag|Portable immobilization and fixation device with calibration unit for x-ray stereomicrographs.|
    CN109906354A|2016-09-01|2019-06-18|海克斯康测量技术有限公司|Uniformity test artifact for coordinate measuring machine|
    US10417785B2|2016-11-16|2019-09-17|Pixameter Corp.|Image calibration for skin lesions|
    US10565735B2|2016-11-16|2020-02-18|Pixameter Corp.|Image calibration patient identification|
    US10298780B2|2016-11-16|2019-05-21|Pixameter Corp.|Long range image calibration|
    US10539515B2|2018-03-30|2020-01-21|Ge Inspection Technologies, Lp|Computed tomographic system calibration|
    US10369698B1|2019-03-07|2019-08-06|Mujin, Inc.|Method and system for performing automatic camera calibration for robot control|
    法律状态:
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    申请号 | 申请日 | 专利标题
    GB201107385|2011-05-04|
    GBGB1107385.5A|GB201107385D0|2011-05-04|2011-05-04|Medical imaging calibration device|
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