Method for producing a three-dimensional anatomical model of a body section|

Abstract

The invention relates to a method for creating a three-dimensional anatomical model of a body section comprising the following steps: (A) arranging a marker made from a marker material on the body section; (B) generating a first ultrasound image of a first detection region of the body section, so that a first marker image of at least part of the marker is visible on the first ultrasound image, wherein the first detection region has a first detection position relative to the marker and a first detection location in the body section; (C) generating a second ultrasound image of a second detection region of the body section, so that a second marker image of at least part of the marker is visible on the second ultrasound image, wherein the second detection region has a second detection position relative to the marker and a second detection location in the body section; (D) determining the first and second detection position and the first and second detection location in a model coordinate system at least also from the first and second marker image; (E) determining structural information of the body section in the first and second detection region from the ultrasound images; (F) combining the structural information of the first and second detection region with the detection position and the detection location of the first and second detection region in the model coordinate system so that a three-dimensional anatomical model is produced.

Description

[0001] Method for producing a three-dimensional anatomical model of a body section

[0002] The invention relates to a method for producing a three-dimensional anatomical model of a body portion. The invention also relates to a system for carrying out such a method for producing a three-dimensional anatomical model of a body portion and to a skin overlay for use in such a system.

[0003] A three-dimensional anatomical model is a physical or digital representation of, for example, a section of a human body. A three-dimensional anatomical model extends in three dimensions—length, width, and height—to illustrate the spatial arrangement and relationship of the anatomical structures within the body. In a preferred embodiment, the three-dimensional anatomical model is a digital representation in which, for example, the view of the model can be changed and complex analyses can be performed.

[0004] Three-dimensional anatomical models of a body part are used, for example, to support the understanding of human anatomy in medical training, to improve surgical planning, and to understand the anatomy in an amputation stump so that an anatomically correct prosthesis fitting can be carried out. The aim is to obtain information about the internal structure of a body part, especially an amputation stump, and to determine, for example, the location of bones, muscles, and other types of tissue. This information can then be used to create a three-dimensional anatomical model of the body part and to manufacture a customized prosthesis, particularly a prosthetic socket.

[0005] One examination method for obtaining this information is ultrasound measurement. An ultrasound measurement uses an ultrasound probe, which usually serves as both a transmitter and receiver of ultrasound waves. The ultrasound probe generates high-frequency sound waves that are sent into the body. The emitted sound waves spread through the body and hit the various tissues and structures within. When the sound waves hit interfaces between tissues of different densities, such as between skin and muscle or between tissue and organs, they are partially reflected. The reflected sound waves return to the ultrasound probe. The time it takes for the reflected sound waves to return, as well as the strength of the reflected sound waves, depend on the density and structure of the tissues they pass through.The ultrasound device records the reflected sound waves and uses them to calculate the distances to the reflected tissues. Using this data, the device creates an ultrasound image in which the various tissues and organs in the body are displayed differently due to their varying echogenicity. Because the probe transmits the sound waves into the tissue over a two-dimensional surface and also receives them from this tissue, these probes are called 2D probes.

[0006] The most commonly used ultrasound image in ultrasound diagnostics is the two-dimensional ultrasound image, also called a B-mode image. This is a two-dimensional, black-and-white or gray-shaded image that depicts the spatial arrangement of tissues and organs in the body.

[0007] Echogenicity refers to the ability to reflect or transmit ultrasound waves in the context of the surrounding tissue. Based on echogenicity, a structure can be characterized as hypoechoic, hypoechoic, or hyperechoic. Hypoechoic structures appear black in the B-mode image; they contain almost no internal echoes. Examples include cysts, vessels, or water. Hypoechoic structures emit relatively few echoes and are usually darker than the surrounding structures, such as lymph nodes and tumors, but brighter than hypoechoic structures. Hyperechoic structures, on the other hand, emit an echo with an increased density of the sound waves compared to the surrounding structures, such as bone and fatty calcifications.

[0008] Therefore, there are significant efforts in the prior art to obtain a three-dimensional anatomical model through ultrasound measurements. EP 2 873 393 B1 discloses a method for determining the dimensions of a prosthetic socket for an amputation stump, wherein the surface of the amputation stump is scanned and recorded in a scanning step. Subsequently, in a sonographic step, the distribution of various tissue types within the amputation stump is determined in several spaced-apart cross-sections through the amputation stump. From this, in a model creation step, a model of the amputation stump is created, into which a bone model whose position can be changed and its size can be scaled is fitted. A disadvantage is that the data can only be combined into a model if the positions at which the ultrasound sensors are applied to the amputation stump are precisely maintained.

[0009] EP 2 210 562 B1 discloses a system for guided sonography using an ultrasound probe. A projector projects a human-recognizable marker onto the object to be scanned. The ultrasound probe is positioned at these positions to combine the acquired data into a model. With this method, the position of the ultrasound probe is well known, but the orientation of the probe relative to the amputation stump can only be estimated. For example, it is not possible to determine whether the detection area depicted in an ultrasound image is tilted or rotated relative to a desired orientation.

[0010] The invention is based on the object of creating a three-dimensional anatomical model from two-dimensional ultrasound images, the quality of which does not depend on the individual skills of the examiner. The inventive method for creating a three-dimensional anatomical model of a body section comprises the following steps:

[0011] (A) placing a marker made of a marker material on the body portion;

[0012] (B) generating a first ultrasound image of a first detection region of the body portion such that a first marker image of at least a portion of the marker is visible on the first ultrasound image, the first detection region having a first detection position relative to the marker and a first detection location in the body portion;

[0013] (C) generating a second ultrasound image of a second detection region of the body portion such that a second marker image of at least a portion of the marker is visible on the second ultrasound image, the second detection region having a second detection position relative to the marker and a second detection location in the body portion;

[0014] (D) determining the first and second detection positions and the first and second detection attitudes in a model coordinate system at least also from the first and second marker images;

[0015] (E) determining structural information of the body portion in the first and second detection areas from the ultrasound images;

[0016] (F) Combining the structural information of the first and second detection areas via the detection position and the detection orientation of the first and second detection areas in the model coordinate system to form a three-dimensional anatomical model.

[0017] In a first step, the marker is placed on the body section. Preferably, the marker is part of a skin overlay comprising the marker and a base body made of a base body material, wherein the base body material has a different echogenicity than the marker material. In the context of the present invention, a skin overlay is understood to be a piece of material that comes into direct contact with the skin. This is the case, for example, with a piece of material that is placed on the body section, for example an amputation stump. In another embodiment, the skin overlay is, for example, part of a seat and / or a lying surface on which the patient is placed, for example by the patient sitting on the seat or lying on the lying surface. The only important thing is that the marker comes into contact with the skin in the first method step (A).

[0018] In a preferred embodiment, the marker rests directly on the skin of the body portion, for example, as part of a skin overlay, without any air or liquid between the marker and the skin of the body portion. This has the advantage that no additional medium needs to be traversed by the ultrasound waves between the skin and the marker, thus achieving higher resolution.

[0019] In a second step, a first ultrasound image of a first detection region of the body portion is generated such that a first marker image of at least a portion of the marker is visible on the first ultrasound image, the first detection region having a first detection position relative to the marker and a first detection location in the body portion. The detection region is the region of a body part, for example an amputation stump, that can be displayed in an ultrasound image. The detection region of the body portion is the volume of the body portion into which ultrasound waves entered to create the ultrasound image and from which reflected ultrasound waves were detected. The ultrasound image shows the structural information of the body portion in the detection region. It is typically a slice of a predetermined thickness determined by the height of the ultrasound probe.Such a disc can be clearly defined if its detection relative to the marker and its detection position relative to the body segment are clearly known. An ultrasound image is a two-dimensional image acquired during an ultrasound examination.

[0020] To generate the ultrasound image, the ultrasound probe is positioned so that the ultrasound waves are emitted into the body section, and the reflected ultrasound waves are detected by the ultrasound probe. The ultrasound waves strike at least a portion of the marker, which at least partially reflects them. The structure that appears in the ultrasound image due to these ultrasound waves reflected by the marker is the marker image.

[0021] In a third step (C), a second ultrasound image of a second detection region of the body portion is generated, such that a second marker image of at least a portion of the marker is visible on the ultrasound image, wherein the second detection region has a second detection position relative to the marker and a second detection orientation in the body portion. For this purpose, the ultrasound probe is preferably moved relative to the body portion. The ultrasound probe has a position and an orientation relative to the body portion that influence the position and orientation of the detection region and preferably completely determine it. The latter means that the detection region can be unambiguously determined and is fixed based on knowledge of the technical parameters of the ultrasound probe and the position and orientation of the ultrasound probe relative to the body portion.The first ultrasound image is generated when the ultrasound probe is in a first position and a first orientation relative to the body portion. If the same ultrasound probe is to be used for the second ultrasound image, it must be moved relative to the body portion, changing the position and / or orientation of the ultrasound probe relative to the body portion.

[0022] Such a movement can be a pure displacement, so that only the position of the ultrasound probe changes relative to the body section, without the orientation being affected. Alternatively, the movement can also be a pure rotation of the ultrasound probe relative to the body section, so that only the orientation of the ultrasound probe to the body section changes, without the position being affected. As a rule, the movement is a superposition of a displacement and a rotation, each of which can be composed of several components. In particular, a rotation can be composed of several individual rotations around different axes of rotation, which do not have to take place one after the other, but can do so. In a further step (D), the first and second detection positions and the first and second detection orientations in a model coordinate system are determined at least also from the first and second marker images.This determines the relative position and orientation of the detection regions to one another. If the two detection positions and the two detection orientations are known, the two detection regions can be positioned in the common model coordinate system and thus combined. According to the invention, the two detection positions and the two detection orientations are determined at least also from the two marker images. It is therefore not necessary to determine all four of these variables from the marker images, even if this is a preferred embodiment. In other embodiments, the first detection position and / or the second detection position is already known because, for example, the position at which the ultrasound probe was placed on the body section is known relative to the marker. In this case, therefore, only the detection orientations are determined from the marker images.

[0023] Preferably, the first detection position and the first detection orientation of the first detection region relative to the marker are determined from the first marker image. Preferably, the second detection position and the second detection orientation of the second detection region are determined from the second marker image.

[0024] According to the invention, the marker is therefore designed such that it is possible to determine the detection position of the imaged detection area from its marker image in an ultrasound image. This can be achieved, for example, by the marker having a geometric shape designed such that sections along different cutting planes have different cutting geometries. If one of these known cutting geometries is identified in an ultrasound image, the detection position of the imaged detection area can be deduced. In a preferred embodiment, the respective ultrasound image is processed before the information is determined, for example, using an image processing program.

[0025] In a further step (E), structural information of the body segment in the first and second detection areas is determined from the ultrasound images. Structural information refers to the external contour of the body segment and the internal structures such as muscle tissue, fatty tissue, bones, and tendons. The determination of structural information can be automated using computer software.

[0026] It is also conceivable that the structural information from the ultrasound images could be expanded or supplemented by information from other sources, such as other measurement methods. The order in which the structural information, the detection position, and the detection orientation are determined from the ultrasound images is irrelevant to the method. It is also possible for the structural information, the detection position, and / or the detection orientation to be determined from the first ultrasound image before the second ultrasound image is acquired.

[0027] In a method step (F), the structural information of the first and second detection areas is combined in the model coordinate system via the detection position and the detection orientation of the first and second detection areas, thus creating a three-dimensional anatomical model. The combination of the structural information via the detection positions and detection orientations is preferably carried out using computer software, resulting in a digital three-dimensional anatomical model.

[0028] One advantage of the method is that an existing two-dimensional ultrasound device can be used unchanged and as usual. For example, no documentation or automated recording of the ultrasound probe's movement is required. Using the marker as a reference, not only the detection position but also the detection orientation can be determined, which offers a decisive advantage in terms of the accuracy of the anatomical model compared to methods in which a specific detection orientation must be maintained manually or determined solely from image material without a reference.

[0029] In a preferred embodiment, a third ultrasound image is generated in a third detection region, wherein a third marker image of at least a portion of the marker is visible in the third ultrasound image, wherein the third detection region has a third detection position relative to the marker and a third detection orientation in the body portion. The third detection position and the third detection orientation in the model coordinate system are determined at least also via the third marker image. The structural information is determined from the third detection region and is introduced into the three-dimensional anatomical model via the third detection position and the third detection orientation in the model coordinate system.Preferably, more than three ultrasound images are generated and evaluated in this way, so that the structural information contained in each image is incorporated into the anatomical model, thus further completing it. It is important that each of the ultrasound images acquired in this way contains a marker image of at least part of the marker, allowing positioning relative to this marker.

[0030] In a further preferred embodiment, there are a plurality of ultrasound images, so that structural, positional, and location information is preferably available over the entire body section. This allows the creation of a three-dimensional anatomical model that is as complete as possible.

[0031] It is irrelevant for the procedure whether all ultrasound images are recorded first or whether the structural information, the detection position and / or the detection location are determined directly from the recorded ultrasound image.

[0032] An iterative process is also possible, in which, for example, the structural information, detection position, and detection orientation are determined from each acquired ultrasound image and then the structural information is incorporated into the existing three-dimensional anatomical model. The process can then be repeated until sufficient structural information is available and incorporated into the model.

[0033] In a preferred embodiment, the detection areas are at least partially overlapping, so that at least as many ultrasound images are recorded until the structural information of each detection area of ​​the body section to be measured can be determined from at least one ultrasound image.

[0034] The invention also achieves the stated object by a system for carrying out a method for creating a three-dimensional anatomical model according to the method described here, wherein the system comprises an ultrasound device, a marker made of a marker material and an electronic controller which is configured to determine detection positions and / or detection locations of detection areas relative to a marker using marker images in ultrasound images, to determine structural information from ultrasound images and to combine the structural information about the detection positions and the detection locations to form a three-dimensional anatomical model.

[0035] The ultrasound device has an ultrasound probe that emits ultrasound waves and detects reflected ultrasound waves, thus creating a two-dimensional ultrasound image.

[0036] In a preferred embodiment, the marker is part of a skin pad comprising the marker and a base body made of a base body material, wherein the base body material has a different echogenicity than the marker material. The skin pad particularly preferably contains silicone. Since the marker material has a different echogenicity than the base body material, both materials reflect the incoming ultrasound waves with different intensities and thus produce distinguishable images in the respective ultrasound image. In a preferred embodiment, the marker has a higher echogenicity than the base body material, such that the marker is more clearly visible in the ultrasound image than the base body material. This allows the scattering pattern of the ultrasound waves reflected by the marker to be better detected.

[0037] In a further preferred embodiment, the marker preferably has a higher echogenicity than skin. This is advantageous because it allows the marker to be clearly distinguished from the skin in the ultrasound image, thus allowing at least a partial detection of the outer contour of the body section being examined.

[0038] In a preferred embodiment, the marker material contains glass and / or plastic and / or a metal, in particular aluminum.

[0039] In a particularly preferred embodiment, the base body material is at least partially silicone and / or the marker material is at least partially a mixture of silicone and glass and / or plastic and / or a metal, in particular aluminum. The marker material can, for example, have particle sizes between 1 μm and 100 μm and / or can be mixed with silicone, for example, in a proportion of more than 5 percent by weight, preferably more than 6 percent by weight, particularly preferably more than 7.5 percent by weight, and in a proportion of less than 75 percent by weight, preferably less than 60 percent by weight, particularly preferably less than 15 percent by weight. It has proven advantageous if the marker is arranged in the base body material, wherein the side of the marker facing the skin is particularly preferably not covered by the base body material. The base body material preferably has a higher echogenicity than air.This allows the outer contour of the main body to be checked in the ultrasound image.

[0040] In a further preferred embodiment, the base body material has a lower or higher echogenicity than skin. It is advantageous for the base body material to have a different echogenicity than skin, so that the base body material can be distinguished from the skin in the ultrasound image. This allows the outer contour of the body section in the skin region to be identified in the ultrasound image by the base body resting on the skin.

[0041] In a preferred embodiment, the marker has at least two or more marker sections. It is important that, even if the marker has multiple marker sections, it is designed in such a way that an assignment of detection position and / or detection positions from the respective marker image is possible. For this purpose, it is advantageous, for example, if the position and / or orientation of the various marker sections relative to one another is known when they are arranged on the body section. This is particularly easy to do if the various marker sections are arranged in the base body material of a base body or a skin overlay. Alternatively, the various marker sections can also be arranged directly and separately on the body section, for example by being glued on. The positions and / or orientations of the various marker sections relative to one another can then be adjusted, for example by hand.Alternatively, the marker fragments and their position on the body part are recorded electronically, for example photographed, filmed or scanned, and then evaluated electronically.

[0042] The individual marker sections can be identically designed. In this case, the assignment of detection position and / or detection positions can be achieved if the individual identically designed marker sections are arranged in a particular arrangement relative to one another, for example in a predetermined pattern, on the body section. Alternatively, at least some marker sections are designed differently. They can differ in the type of marker material, their length, width and / or thickness and / or their geometric shape. Of course, a combination is also possible in which some of the marker sections are identical and some are designed differently from one another. Particularly preferably, at least one of the marker sections, but advantageously all marker sections, is designed such that geometric projections of the individual marker sections onto different planes result in different geometric shapes.When creating an ultrasound image, ultrasound waves strike the respective marker segment and are reflected. The geometric shape of the marker segment in the resulting ultrasound image corresponds to the projection of the marker segment onto a plane perpendicular to the propagation of the ultrasound waves. If this projection results in different geometric shapes for different planes, the detection position can be determined from a single ultrasound image. Advantageously, the individual ultrasound images are recorded in such a way that more than one marker segment, preferably at least two, and particularly preferably at least four marker segments, generate a marker image.

[0043] In a preferred embodiment, a different marker image is acquired during the ultrasound measurement of each of the at least two marker segments. The different marker images can be achieved, in particular, by different sizes and / or thicknesses and / or densities and / or geometries and / or orientations and / or marker materials of the marker segments.

[0044] A marker segment with a different geometry than another segment will reflect ultrasound waves differently, for example, in a different direction and / or with different scattering. Likewise, the orientation of the marker segment in the skin overlay may produce a distinguishable marker image if the ultrasound waves hit a differently shaped marker surface due to the orientation and are therefore scattered differently.

[0045] In a preferred embodiment, the marker image can be clearly assigned to the marker section through whose ultrasound measurement the marker image was created.

[0046] More preferably, the skin overlay comprises a marker consisting of a plurality of marker segments, wherein the arrangement of the marker segments in the skin overlay is known. This is advantageous because it enables the ultrasound images to be assigned to the detection position and the detection orientation. In a particularly preferred embodiment, the skin overlay comprises a marker with a plurality of marker segments, wherein the marker segments are configured such that the marker images form an individual pattern, via which the detection position and / or the detection orientation can be clearly determined.

[0047] For example, this can be achieved by creating a unique shape for each marker segment, thus creating a unique marker image. Alternatively, a unique pattern can be created from a limited number of different marker segment geometries.

[0048] The individual pattern allows for more marker sections to be used in the skin overlay, allowing a large body section to be measured with great accuracy.

[0049] Further preferably, the detection position in the body section is encoded via the arrangement of the marker segments. For example, the detection positions are encoded by four adjacent marker segments. This is advantageous because, for example, in a femoral stump, not only the relative position of the detection areas to each other can be determined, but also which side of the model is located dorsal or ventral.

[0050] The farther the ultrasound probe is from the marker, the fewer ultrasound waves reach the marker and / or the more strongly the ultrasound waves have already been scattered by the medium they are traversing. Consequently, it is advantageous if a marker consisting of multiple marker segments presents a larger surface for reflecting the ultrasound waves at a greater distance from the ultrasound probe than at a closer distance. It is therefore advantageous to arrange marker segments with a larger diameter or contour at the points on the body segment with the larger diameter. On a transfemoral amputation stump, this means that the larger marker segments are arranged proximally.In a preferred embodiment, the skin patch therefore comprises a marker composed of a plurality of marker segments, wherein the marker segments present at least two differently sized surfaces from which the ultrasound waves are reflected. This has the advantage of improving resolution.

[0051] In a preferred embodiment, the marker sections are larger when the ultrasound probe is applied to the opposite side of the body section, such as in a skin pad for a treatment chair.

[0052] In a further preferred embodiment, the ultrasound probe is placed at a location with smaller marker segments and the ultrasound waves are emitted into the body segment in such a way that larger marker segments on the opposite side are hit by the ultrasound waves and reflected by them.

[0053] In a preferred embodiment, the marker segments have at least two different geometric shapes, such as different polyhedra, pyramids, cubes, or prisms. This is advantageous because it allows the detection position and orientation to be determined more precisely.

[0054] In a further preferred embodiment, the skin pad has at least one contact point at which the ultrasound probe is placed on the skin pad.

[0055] In a further preferred embodiment, the skin pad does not have a marker in the area where the ultrasound probe is applied. This is advantageous because the reflection of the marker before the ultrasound waves enter the body section impairs the resolution of the ultrasound image.

[0056] In a preferred embodiment, the skin pad is so flexible overall that it can be applied to the skin over a larger area, following the curvature of the body part. For example, the skin pad extends over the entire thigh of a person.

[0057] In a preferred embodiment, the skin pad is pre-shaped for measuring a specific body portion and / or molded to a body portion. For example, the skin pad is a support surface on which the patient is placed. In another example, the skin pad is integrated into a patient couch or treatment chair.

[0058] In a preferred embodiment, the skin pad at least partially, but preferably completely, encloses the body part when applied as intended. The skin pad completely encloses the body part when the skin pad extends over the entire skin of the body part.

[0059] In a further preferred embodiment, the skin overlay is a liner for an amputation stump. This is particularly advantageous when the body portion is an amputation stump, such as a lower leg stump, a femoral stump, an upper arm stump, or a forearm stump.

[0060] A liner, also called a prosthetic liner, in many applications forms an intermediate layer and / or an interface between the amputation stump and a prosthetic socket of a prosthesis, which is arranged and preferably also attached to the amputation stump. A prosthetic liner has an open proximal end and an opposite closed distal end. A prosthetic liner is preferably elastic and is expanded and / or stretched when applied to the amputation stump. When a liner is stretched, this means that its longitudinal extent, i.e. its extent from the proximal end to the distal end, increases. When a liner is expanded, this means that the circumference of the liner increases, preferably in a plane perpendicular to the longitudinal extent. When a prosthetic liner is applied to an amputation stump, the liner is preferably both stretched and expanded.Due to its expansion and / or stretching and elasticity, the liner exerts a compressive effect on the amputation stump to which it is applied. The liner is preferably elastic enough to be applied to the amputation stump like a stocking. It is preferably rolled up from the proximal end, preferably until a distal end of the amputation stump can be placed against the inner surface of the distal end of the prosthetic liner. The liner is then unrolled onto the amputation stump. The amputation stump is then placed in the prosthetic liner.

[0061] For application within the scope of the present invention, a skin pad can also be used which has a plurality of strips made of polyurethane and / or silicone, each carrying at least one marker. These strips preferably have a width of several centimeters, for example 8 cm, 10 cm, or 15 cm. They can be connected to one another directly or indirectly at their respective distal ends. They are preferably each arranged on a positioning ring. To apply this type of skin pad, this is placed on a distal end of the amputation stump so that the individual strips extend from this positioning ring in a proximal direction along the amputation stump. Since such a skin pad does not exert a compression effect, it is advantageous to attach it to the amputation stump, for example by pulling a cover, such as a textile cover, over the skin pad arranged on the amputation stump.

[0062] In a preferred embodiment, the at least one marker is located on or in the base material from which the liner is made. Since the position and / or orientation of the prosthetic liner on the amputation stump is not, or at least not always, completely reproducible, the position and / or orientation of the marker relative to the amputation stump is also not always completely reproducible. The base material of the prosthetic liner is, for example, a polyurethane (PU) and / or a silicone. Preferably, the prosthetic liner does not have a textile layer or ply. This is not necessary, for example, if the prosthetic liner, which forms the skin overlay, is not intended to be or is not worn permanently by the patient, but is, for example, only applied for the duration of one of the procedures described here.

[0063] The base material is a 3-dimensional material. In this case, this means that the prosthetic liner has a wall that surrounds the amputation stump when in place and that has a thickness that allows the marker to be arranged within the wall and thus within the base material. Preferably, several markers are arranged on and / or in the base material of the skin overlay, in particular the prosthetic liner. Particularly preferably, these several markers have different distances from the inner surface of the liner and thus, when the liner is in place, also from the amputation stump. Preferably, at least one marker is arranged on the inner surface of the liner. Preferably, at least one marker is arranged on the outer surface of the liner. Preferably, at least one marker is arranged within the base material of the liner, for example, cast in and completely surrounded by the base material.Particularly preferably, several markers are arranged within the base material, wherein these markers are particularly preferably at different distances from the inner surface of the liner.

[0064] Preferably, the base material of the liner has a similar echogenicity to the tissue of the amputation stump, preferably the same, at least near the skin. In this respect, polyurethane is preferable to silicone.

[0065] In a preferred embodiment, the marker has at least one cavity within the base material, which is preferably filled with air. As a result, it has a different echogenicity than the surrounding base material and is detectable in ultrasound images. The marker particularly preferably has several such cavities. The cavities are preferably flexible tubes arranged in the base material of the prosthetic liner. The tubes particularly preferably cross each other in the base material. To ensure that only the cavities are detectable in the ultrasound images, it is advantageous if the tubes are made from the base material. The tubes particularly preferably have different diameters so that they can be distinguished in ultrasound images. The wall of the liner preferably has a greater thickness at the points where the tubes run.This makes the markers visible both in the near field, i.e. when detected by an ultrasonic sensor arranged on the same side as the markers, and in the far field, i.e. when detected by an ultrasonic sensor arranged on the opposite side to the markers.

[0066] If tubes are used as markers, it is advisable to lay them at different levels and to provide different connections and / or intersection points between the tubes in order to enable the spatial position of the ultrasound probe to be determined. A intersection point is preferably any point where the images of two tubes cross in the ultrasound image. The tubes involved can also run one behind the other from the perspective of the ultrasound device, in particular the ultrasound head. This also leads to an intersection point in the ultrasound image. Of course, intersection points are also places where two or more tubes actually cross, so that it is in principle possible to direct fluid from one tube to another. Ideally, tubes with different diameters are used so that they can be separated from one another.The echogenicity of the air pockets in the tubes should not be too high. This prevents shadows from forming. The molded-in tube should preferably be flexible enough to allow the liner to be rolled up.

[0067] The invention is particularly advantageous for incorporating anatomical models for the production of a prosthetic socket. A prosthesis usually has a prosthetic socket into which the amputation stump is inserted. The prosthetic socket is usually made of a rigid material, such as a carbon fiber composite. In particular, with leg prostheses with which the patient walks or runs, large forces act on both the prosthetic socket and the amputation stump. To avoid painful pressure points, it is of great importance that the prosthetic socket, which is usually made individually for the wearer of the prosthesis, is adapted as closely as possible to the external shape and the anatomical distribution of bones, muscles, tendons, and fatty tissue of the amputation stump.

[0068] Bony parts are particularly sensitive to pressure and therefore need more protection than soft tissues, which deform under the stress of walking or standing.

[0069] For this reason, it is particularly advantageous to compress the amputation stump during the creation of the at least three-dimensional model, i.e. in particular to apply pressure, and to modify it with a functional shape, the liner. This is referred to as pre-compression. Applying the liner often changes the position of the markers relative to one another. This is preferably taken into account during production of the liner. For example, calibration can be carried out by measuring and comparing the target and actual distances. Knowing the actual distances can be used to calculate deviations, which are then compensated for during the actual procedure. Alternatively or additionally, the area of ​​the markers in the liner is manufactured in such a way that elasticity and thus deformation are limited by suitable measures, such as textile reinforcements.

[0070] In a third aspect, the invention relates to a skin patch for use in a system and a method described herein.

[0071] The following figures show examples of possible embodiments.

[0072] Fig. 1 shows the body section to be measured, in this example a

[0073] Thigh stump 10 in the dorsal view. Also visible are the skin overlay 12, the base body 13, and the marker 14, which in this example consists of a plurality of marker sections and forms an individual pattern. The individual pattern encodes the detection position and the detection orientation of the recorded ultrasound images relative to the marker. Also visible are three ultrasound probes 16, which are guided freely over the skin overlay and emit ultrasound waves into the thigh stump. Alternatively, just one ultrasound probe 16 can be used, which is arranged at different positions and / or in different orientations on the body section. Fig. 1 also shows that the skin overlay rests directly on the skin in certain areas, while in the lower area of ​​the thigh stump it has no direct contact with the skin. Fig.1 three partially overlapping detection areas, which are represented by overlapping indicated ultrasonic waves 18.

[0074] Fig. 2 again shows a dorsal view of a femoral stump 10. The skin overlay 12 is in the form of a liner that completely encloses the femoral stump. The skin overlay 12 contains a base body 13 and a pattern of marker segments 14. In this example, the marker segments are represented by two different geometries. The different orientation and sequence create an individual pattern. In addition, the two different geometries are available in two different sizes: the marker segments 14, in this example with a size of approximately 15 mm x 15 mm x 15 mm for measurement from greater distances, and smaller marker segments 14.2 with a size of approximately 2 mm x 2 mm x 2 mm for detection at a shorter distance from the ultrasound probe.In the present example, it is particularly advantageous to position the ultrasound probe 16, as shown, on the side of the thigh stump that has the smaller marker segments 14.2, so that the ultrasound waves impinge on the smaller marker segments 14.2 at a short distance and, after the ultrasound waves have traversed the body portion, impinge on the larger marker segments 14 on the opposite side. Here, too, the ultrasound probes are positioned such that the ultrasound waves 18 are emitted such that the detection areas at least partially overlap. Fig. 3 shows a cross-section 20 of a thigh with a skin overlay 12 with several marker segments, the femur 40, the muscle tissue 42, and the outer tissue 44 of skin and fat surrounding the femur muscle. This structural information can be obtained from the ultrasound image.The skin pad 12 completely encloses the examined body section in this area.

[0075] Fig. 4 shows a cross-section 20 of a thigh with a skin pad 12, which has a base body 12, several marker sections 14 and smaller marker sections 18. The skin pad further shows contact points 30 at which the ultrasound probe 16 is to be placed on the skin pad. Fig. 4 shows that the smaller marker sections 14.2 are arranged in the area of ​​the contact points 30, ensuring that the small marker sections are used at a shorter distance from the ultrasound probe. The larger marker sections 14 are arranged on the opposite side of the smaller marker sections 14.2. This is particularly advantageous because the ultrasound waves emitted by the ultrasound probe 16 first hit the smaller marker sections 14.2 and are partially reflected, and then hit the larger marker sections 14 at a greater distance and are partially reflected there.

[0076] Fig. 5 shows an exemplary combination of two different geometries of marker segments 14, with which the detection position and detection orientation can be determined from a two-dimensional marker image. With these sequences of four marker segments per line, positions in the skin overlay can also be coded relative to the rest of the body.

[0077] Fig. 6 shows a skin pad 52 arranged on a treatment table 54. The body part to be measured, in this case a pelvis, is located on the skin pad 52. The ultrasound probe 16 emits ultrasound waves through the body part to be measured to the skin pad 52 with the marker sections 14, which are suitable for larger distances. For example, the marker sections have a size of 15 mm x 15 mm. The ultrasound waves 18 are reflected by the marker sections 14 of the skin pad 12 and detected by the ultrasound probe 16. Reference list

[0078] 10 Femoral stump

[0079] 12 Skin pad 13 Base body

[0080] 14 marker sections

[0081] 14.2 smaller marker sections

[0082] 16 Ultrasound probe

[0083] 18 Ultrasonic wave 20 Cross section

[0084] 40 femurs

[0085] 42 thigh muscle

[0086] 44 outer tissue

Claims

Patent claims 1. A method for creating a three-dimensional anatomical model of a body section comprising the following steps: (A) placing a marker made of a marker material on the body portion; (B) generating a first ultrasound image of a first detection region of the body portion such that a first marker image of at least a portion of the marker is visible on the first ultrasound image, the first detection region having a first detection position relative to the marker and a first detection location in the body portion; (C) generating a second ultrasound image of a second detection region of the body portion such that a second marker image of at least a portion of the marker is visible on the second ultrasound image, the second detection region having a second detection position relative to the marker and a second detection location in the body portion; (D) determining the first and second detection positions and the first and second detection attitudes in a model coordinate system at least also from the first and second marker images; (E) determining structural information of the body portion in the first and second detection areas from the ultrasound images; (F) Combining the structural information of the first and second detection areas via the detection position and the detection orientation of the first and second detection areas in the model coordinate system to form a three-dimensional anatomical model.

2. Method for creating a three-dimensional anatomical model of a body section according to claim 1, characterized in that a third ultrasound image of a third detection area is generated, wherein in the third ultrasound image a third marker image of at least part of the marker is visible on the ultrasound image, wherein the third detection area has a third detection position relative to the marker and a third detection location in the body section, wherein the third detection position and the third detection location in the model coordinate system are determined at least also via the third marker image, the structural information is determined from the third detection area and the structural information of the third detection area is introduced into the three-dimensional anatomical model via the third detection position and the third detection location in the model coordinate system.

3. System for carrying out a method according to one of the preceding claims, comprising - an ultrasound device; - has a marker made of a marker material; - an electronic control system set up for - Determining detection positions and / or detection positions of detection areas relative to a marker, wherein the determination is carried out using marker images in ultrasound images, - Determining structural information from ultrasound images, and - Combining the structural information about the detection positions and the detection layers into a three-dimensional anatomical model.

4. System according to claim 3, characterized in that the marker is part of a skin overlay comprising the marker and a base body made of a base body material, wherein the base body material has a different echogenicity than the marker material.

5. System according to claim 4, characterized in that - the base material has a higher echogenicity than air and / or - the base body material has a lower or higher echogenicity than skin and / or - the base body material has a lower echogenicity than the marker material.

6. System according to one of claims 3 to 4, characterized in that - the marker has a higher echogenicity than the base body material and / or - the marker has a different, in particular higher, echogenicity than skin and / or - the marker material contains glass and / or plastic and / or a metal, in particular aluminum.

7. System according to one of claims 3 to 6, characterized in that - the marker consists of at least two marker sections which produce a different marker image, wherein the different marker images are achieved in particular by a different size and / or thickness and / or density and / or geometry and / or orientation and / or marker materials of the marker sections.

8. System according to claim 7, characterized in that - the skin overlay has a marker consisting of a plurality of marker sections which form a known individual pattern by means of which the detection position and / or the detection orientation can be clearly determined.

9. System according to one of claims 3 to 8, characterized in that - the skin pad has at least one contact point for an ultrasound device.

10. System according to one of claims 3 to 9, characterized in that - the skin pad is pre-shaped for measuring a specific body part and / or is shaped to fit a body part.

11. System according to one of claims 3 to 10, characterized in that - the skin pad is a liner for an amputation stump.

12. A skin patch for use in a system according to any one of claims 3 to 11.

13. Skin pad according to claim 12, characterized in that the skin pad is a prosthetic liner.

Images