PATTERNED INCISION FOIL AND METHOD FOR DETERMINING A GEOMETRY OF AN ANATOMICAL SURFACE

Abstract

An incision foil made of a sterile, thin adhesive plastic film with a defined pattern printed on it (e.g. a fine grid pattern) can be stuck e.g. on a patient's skin surface and which marks the anatomical region of interest. Using a camera, images are acquired of the attached film and the deformation of the pattern is digitized. With a computer vision algorithm the surface of the patient, which corresponds to the surface of the film, is reconstructed from the detected pattern features in the images in comparison to the known original undeformed pattern. A method determines a geometry of the surface of the patient using the incision foil.

Claims

1.-22. (canceled)

23. A system comprising: an incision foil comprising: a first side comprising an adhesive portion; a non-adhesive second side opposite the first side; and a pattern provided on the incision foil; a detection device operable to detect the pattern provided on the incision foil; an electronic data storage device storing pattern template data describing a predetermined pattern in a known geometry of the incision foil; and a computer coupled with the detection device and with the electronic data storage device, the computer being operable to receive, from the detection device, pattern detection data describing an appearance of the pattern detected by the detection device, the computer being operable to receive pattern template data from the electronic data storage device, wherein the computer is configured to determine, based on the pattern detection data and the pattern template data, surface geometry data describing a geometry of the incision foil.

24. The system according to claim 23, wherein the pattern is provided on a portion of the non-adhesive side of the incision foil at a position opposite the adhesive portion.

25. The system according to claim 23, wherein the appearance of the pattern detected by the detection device changes when the incision foil is deformed.

26. The system according to claim 23, wherein the pattern comprises a regular pattern.

27. The system according to claim 26, wherein the regular pattern comprises a symmetric pattern or a periodic pattern.

28. The system according to claim 23, wherein the pattern comprises an irregular pattern.

29. The system according to claim 28, wherein the irregular pattern comprises an unsymmetric pattern or an aperiodic pattern.

30. A computer-implemented method of determining a geometry of an anatomical surface of an associated anatomical body part, the method comprising: acquiring pattern detection data that describes an appearance of a pattern provided on an incision foil having a first side comprising an adhesive position and a non-adhesive second side opposite to the first side, wherein the pattern is provided on the incision foil, wherein the adhesive portion of the incision foil is attached to the anatomical surface of the anatomical body part; determining surface geometry data based on the pattern detection data, wherein the surface geometry data describes the geometry of the anatomical surface; acquiring pattern template data describing a predetermined foil appearance of the pattern in a predetermined geometry of the incision foil; and determining, based on the pattern detection data and the pattern template data, surface geometry data describing the geometry of the anatomical surface of the associated anatomical body part.

31. The method according to claim 30, wherein: the determining the surface geometry data comprises determining the surface geometry by a surface reconstruction using mono-photogrammetry or stereo-photogrammetry.

32. A computer-readable storage medium storing instructions that, when the instructions are executed by a computer, cause the computer to perform a method of determining a geometry of an anatomical surface of an associated anatomical body part by: acquiring pattern detection data that describes an appearance of a pattern provided on an incision foil having a first side comprising an adhesive position and a non-adhesive second side opposite to the first side, wherein the pattern is provided on the incision foil, wherein the adhesive portion of the incision foil is attached to the anatomical surface of the anatomical body part; determining surface geometry data based on the pattern detection data, wherein the surface geometry data describes the geometry of the anatomical surface; acquiring pattern template data describing a predetermined foil appearance of the pattern in a predetermined geometry of the incision foil; and determining, based on the pattern detection data and the pattern template data, surface geometry data describing the geometry of the anatomical surface of the associated anatomical body part.

33. The computer-readable storage medium according to claim 32, wherein: the determining the surface geometry data comprises determining the surface geometry by a surface reconstruction using mono-photogrammetry or stereo-photogrammetry.

34. A computer system comprising: at least one processor; and a computer-readable storage medium storing instructions that, when the instructions are executed by the at least one processor, cause the at least one processor to perform a method of determining a geometry of an anatomical surface of an associated anatomical body part by: acquiring pattern detection data that describes an appearance of a pattern provided on an incision foil having a first side comprising an adhesive position and a non-adhesive second side opposite to the first side, wherein the pattern is provided on the incision foil, wherein the adhesive portion of the incision foil is attached to the anatomical surface of the anatomical body part; determining surface geometry data based on the pattern detection data, wherein the surface geometry data describes the geometry of the anatomical surface; acquiring pattern template data describing a predetermined foil appearance of the pattern in a predetermined geometry of the incision foil; and determining, based on the pattern detection data and the pattern template data, surface geometry data describing the geometry of the anatomical surface of the associated anatomical body part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In the following, the invention is described with reference to the appended figures which give background explanations and represent specific embodiments of the invention. The scope of the invention is however not limited to the specific features disclosed in the context of the figures, wherein

[0057] FIG. 1 shows a dotted pattern usable on the incision foil;

[0058] FIG. 2 shows a rectangular pattern usable on the incision foil;

[0059] FIG. 3 shows a dotted pattern with embedded index codes;

[0060] FIG. 4 shows a rectangular pattern with embedded index codes;

[0061] FIG. 5 illustrates a deformation of the pattern;

[0062] FIG. 6 illustrates a first type of irregular pattern;

[0063] FIG. 7 illustrates a second type of irregular pattern;

[0064] FIG. 8 illustrates an application of the incision foil attached to an anatomical body part;

[0065] FIG. 9 illustrates the basic steps of the method according to the first aspect; and

[0066] FIG. 10 is a schematic illustration of the system according to the second aspect; and

[0067] FIG. 11 shows an embodiment of the present invention, specifically the method according to the first aspect.

DESCRIPTION OF EMBODIMENTS

[0068] FIGS. 1 and 2 illustrate types of regular, specifically periodic, patterns usable on the incision foil according to the first aspect. FIG. 1 shows a pattern of finite size consisting of a continuous arrangement of dots of all the same size at constant spacing between one another. FIG. 2 shows a pattern consisting of lines defining a continuous arrangement quadratic rectangles of finite size, the rectangles all being of the same size.

[0069] FIGS. 3 and 4, respectively, show the patterns of FIGS. 1 and 2, respectively, with additionally an index code, for example a grid index code such as a QR code, embedded in the dots or rectangles, respectively. In these examples, the pattern includes markers with known one-to-one correspondence to their position and/or orientation relative to the pattern, which allows to orient the pattern correctly in camera coordinates and allows to identify the pattern even if parts of the pattern are hidden in trenches (as illustrated in FIG. 5).

[0070] FIG. 5 illustrates the deformation of the incision foil and thus the pattern on it when for example the anatomical surface onto which the incision foil has been attached is deformed. The dots 5 of the pattern change their position in the direction vertical to the plain of the undeformed pattern but maintain their distance to each other since the foil cannot be stretched. Thus, the detection device 6, for example a camera, receives a different image of the pattern compared to the undeformed state. The received image can be analysed using a known algorithm to determine the geometry, for example shape, of the deformed incision foil. This can be done using the characteristic distance calculated from the image of the deformed incision foil. If the undeformed state is known, the change of geometry of the pattern between the undeformed and the deformed state can be used to determine the change of geometry of the underlying anatomical surface and therefore the anatomical body part to which the anatomical surface belongs. FIG. 5 also shows an example which is based on individual feature identification (as in FIGS. 3 and 4) because some features are not visible on the deformed surface from the shown perspective of the camera. A correct one-to-one correspondence of features is therefore only possible if each feature in the camera image can be individually identified. If there is no feature indexing, then one can only rely on counting features in the camera image, which would fail in this case.

[0071] FIGS. 6 and 7 illustrate that the pattern 7, 11 has for example a characteristic distance between its defining constituents. For example, it can be amorphous, quasi-crystalline, periodic or a square pattern. A change in the characteristic distance in the image acquired by the detection device can be used to determine a change in the geometry of the incision foil.

[0072] FIG. 8 shows an incision foil comprising a pattern 7 on its visible surface when it is attached to an anatomical body part 9 of a patient 10. The pattern 7 is detected by a stereo camera comprising two imaging units 8 having the anatomical body part 9 in their field of view.

[0073] FIG. 9 illustrates the basic steps of the method according to the third aspect, in which step S11 encompasses acquisition of the pattern detection data and step S12 encompasses determination of the surface geometry data.

[0074] FIG. 10 is a schematic illustration of the medical system 12 according to the second aspect. The system is in its entirety identified by reference sign 12 and comprises a computer 13, an electronic data storage device (such as a hard disc) 14 for storing at least the patient data and the detection device 8 (such as a camera). The components of the medical system 12 have the functionalities and properties explained above with regard to the second aspect of this disclosure.

[0075] FIG. 11 illustrates an embodiment of the present invention that includes all essential features of the invention. In this embodiment, the entire data processing which is part of the method according to the first aspect is performed by a computer. Reference sign 15 denotes the input of data acquired by the method according to the first aspect into the computer 16 and reference sign 17 denotes the output of data determined by the method according to the third aspect.

[0076] A concise account of the present invention can be worded as follows:

[0077] 1. The incision foil is put on patient's anatomy of interest (skin surface, surface of an organ, cavity). It is sterile so that it can be used during a surgical procedure and be left on the patient even when incisions are performed through it. The incision foil can be designed and used as a surgical incise drape (incision film) which is standard of care in many surgical areas. The incision foil is adhesive, soft and smooth so that it matches and models the patient's anatomy surface as precisely as possible.

[0078] 2. A digital video camera (mono, stereo, or multiple cameras calibrated to each other) captures an image of the attached incision foil. The camera is for example a standard computer vision camera of a head-mounted mixed reality headset, a video camera of a surgical microscope, a video camera integrated in an operation room lamp, or any other image source capturing the scene.

[0079] 3. Images are processed in real time directly on the device the camera is attached to (e.g. mixed reality headset) or sent to a remote computer (located for example in the cloud) for processing.

[0080] 4. Known features of the pattern are detected in the image (e.g. grid lines, corners, intersections) and correspondences to original pattern are determined. The pattern can be coded so that correspondences between image points and points of the printed pattern can be quickly found and 3D information easily be retrieved.

[0081] 5. A point cloud or surface mesh is reconstructed from the calculated point correspondences.

[0082] 6. Procedure can be repeated continuously evaluating captured images in order to: [0083] a. refine a model of the anatomical surface by evaluating images captured from different view angles or improving on resolution (for example, results from all evaluate camera frames are integrated and merged in one refined model); and/or [0084] b. detect changes to the appearance of the surface in the image due to e.g. skin movement and/or tissue shift in real time.