# US 12,758,165 B2 · Moiré marker for x-ray imaging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,758,165 B2 - Document ID: US12758165B2 - Status: Granted - Kind: B2 - Application number: 17/927,063 - Filed: 2020-05-29 - Published: 2023-07-06 - Granted: 2026-10-13 - Earliest claimed: 2020-05-29 - Assignees: Brainlab AG - Applicants: Brainlab AG - Inventors: Sebastian Stopp; Nils Frielinghaus - Web page: https://patentgrep.com/patent/US12758165B2 ## CPC - A61B 6/0492: {using markers or indicia for aiding patient positioning} - A61B 6/52: {Devices using data or image processing specially adapted for radiation diagnosis} - A61B 6/5294: {involving using additional data, e.g. patient information, image labeling, acquisition parameters} - A61B 6/5211: {involving processing of medical diagnostic data} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A computer-implemented method of determining a rotational position of an object in a coordinate system of an x-ray imaging device is provided. An x-ray image is generated of an object to which a Moiré marker for x-ray imaging is attached. The Moiré pattern generated by the Moiré marker is analysed and the rotational position of the marker and hence of the object is determined in a calculative manner. The Moiré marker for x-ray imaging includes a pattern which results in a significantly different appearance when being observed from slightly different perspectives. The Moiré marker for x-ray imaging can include two layers with patterns produced by a material that shields x-ray as good as possible, surrounded and spaced apart by material that is highly transparent in x-ray. ## Claims ### Claim 1 A computer-implemented method of determining a rotational position of an object in a coordinate system of an associated x-ray imaging device, the method comprising: providing an x-ray image of an object to which a Moiré marker for x-ray imaging is attached during generation of the x-ray image, the x-ray image having been generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein a Moiré pattern of x-ray signal intensities is generated on the x-ray image by the Moiré marker for x-ray imaging when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein the Moiré pattern of x-ray signal intensities generated when the object other than the associated x ray imaging device-to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device is indicative of an angle between the Moiré marker for x-ray imaging and an x-ray propagation direction of the associated x-ray imaging device in the coordinate system of the associated x-ray imaging device, wherein the object comprises one or more of: a medical robot, a medical instrument, a medical device, a patient support device, and/or a patient; determining, based on the Moiré pattern of x-ray signal intensities generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, the rotational position of the object in the coordinate system of the associated x-ray imaging device; generating a control signal for positioning the object relative to the x-ray imaging device based on the determined rotational position of the object; and repeating the steps of providing the x-ray image of the object, determining the rotational position of the object, and generating the control signal until a pre-defined position condition describing a desired position of the object in the coordinate system of the x-ray imaging device is reached. ### Claim 2 (depends on 1) The method according to claim 1, wherein the determining the rotational position of the object comprises: determining at least one point in the Moiré pattern of x-ray signal intensities; and using the determined at least one point as an input of a pre-defined relation describing a dependency of the Moiré pattern from the angle between the Moiré marker and the x-ray propagation direction of the x-ray imaging device. ### Claim 3 (depends on 1) The method according to claim 1, further comprising: using the generated control signal to cause a movement of the object. ### Claim 4 (depends on 1) The method according to claim 1, wherein the x-ray image is an x-ray projection image, and the determined rotational position of the object takes into account, in a calculative manner, a spatial divergence of an x-ray beam emitted by the x-ray imaging device. ### Claim 5 (depends on 1) The method according to claim 1, further comprising: automatically detecting the Moiré pattern of x-ray signal intensities in the x-ray image with an image processing algorithm. ### Claim 6 (depends on 2) The method according to claim 2, wherein the determined at least one point represents an x-ray signal intensity minimum of the Moiré pattern or an x-ray signal intensity maximum of the Moiré pattern. ### Claim 7 (depends on 2) The method according to claim 2 wherein the pre-defined relation is a stored x-ray intensity distribution detected by an x-ray sensor of the x-ray imaging device as a function of the angle between the Moiré marker and the x-ray propagation direction of the x-ray imaging device. ### Claim 8 A computer-implemented method of determining a rotational position of an object in a coordinate system of an associated x-ray imaging device, the method comprising: providing an x-ray image of an object to which a Moiré marker for x-ray imaging is attached during generation of the x-ray image, the x-ray image having been generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein a Moiré pattern of x-ray signal intensities is generated on the x-ray image by the Moiré marker for x-ray imaging when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein the Moiré pattern of x-ray signal intensities generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device is indicative of an angle between the Moiré marker for x-ray imaging and an x-ray propagation direction of the associated x-ray imaging device in the coordinate system of the associated x-ray imaging device, wherein the object comprises one or more of: a medical robot, a medical instrument, a medical device, a patient support device, and/or a patient, wherein, in the provided x-ray image, the Moiré marker and a further marker are attached to the object as marker array; determining, based on the Moiré pattern of x-ray signal intensities generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, the rotational position of the object in the coordinate system of the associated x-ray imaging device; and automatically identifying the further marker in the provided x-ray image. ### Claim 9 (depends on 8) The method according to claim 8, the method further comprising: using the automatically identified further marker in the provided x-ray image for calculating a translational position of the Moiré marker within the coordinate system of the x-ray imaging device. ### Claim 10 (depends on 8) The method according to claim 8, wherein the further marker is of an x-ray opaque material and has a ball shape, a cuboid shape, a pyramidal shape, a disc shape, or any combination thereof. ### Claim 11 A computer-implemented method of determining a rotational position of an object in a coordinate system of an associated x-ray imaging device, the method comprising: providing an x-ray image of an object to which a Moiré marker for x-ray imaging is attached during generation of the x-ray image, the x-ray image having been generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein a Moiré pattern of x-ray signal intensities is generated on the x-ray image by the Moiré marker for x-ray imaging when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, wherein the Moiré pattern of x-ray signal intensities generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device is indicative of an angle between the Moiré marker for x-ray imaging and an x-ray propagation direction of the associated x-ray imaging device in the coordinate system of the associated x-ray imaging device, wherein the object comprises one or more of: a medical robot, a medical instrument, a medical device, a patient support device, and/or a patient; and determining, based on the Moiré pattern of x-ray signal intensities generated when the object to which the Moiré marker for x-ray imaging is attached is imaged together with the Moiré marker for x-ray imaging by the associated x-ray imaging device, the rotational position of the object in the coordinate system of the associated x-ray imaging device, wherein the determining the rotational position further comprises comparing at least the Moiré pattern of the x-ray signal intensities generated by the Moiré marker in the x-ray image with a target pattern of x-ray intensities to be generated by the Moiré marker. ### Claim 12 (depends on 11) The method according to claim 11, further comprising: repeating the steps of providing the x-ray image of the object and determining the rotational position of the object, wherein the determining the rotational position of the object comprises comparing at least the Moiré pattern with the target pattern, until a pre-defined match between the generated Moiré pattern in the provided x-ray image and the target pattern is achieved. ### Claim 13 A Moiré marker for x-ray imaging, the Moiré marker for x-ray imaging comprising: a layered pattern structure of a plurality of layers comprising at least a first material and a second material, wherein the first material has a higher x-ray opacity than an x-ray opacity of the second material, wherein pattern structures of the first and second materials are configured for generating a Moiré pattern of x-ray signal intensities in an x-ray image when being imaged by an associated x-ray imaging device, wherein the layered pattern structure further comprises: a first layer with a first pattern of the first material and the second material; and a second layer with a second pattern of the first material and the second material. ### Claim 14 (depends on 13) The Moiré marker for x-ray imaging according to claim 13, wherein the layered pattern structure of the first material and the second material is configured to allow a determination of a rotational position of the Moiré marker for x-ray imaging from the x-ray image of the Moiré marker for x-ray imaging. ### Claim 15 (depends on 13) The Moiré marker for x-ray imaging according to claim 13, wherein the first layer and the second layer are separated from each other by a first distance, wherein the second material of the first pattern and the second material of the second pattern have a first width between two adjacent pattern elements of the first material, and the first distance is larger than the first width. ### Claim 16 (depends on 13) The Moiré marker for x-ray imaging according to claim 13, wherein the first material comprises at least one of lead, tin, bismuth, tungsten, iodine, gold, tantalum, yttrium, niobium, molybdenum, ruthenium, rhodium, barium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, rhenium, osmium, iridium, or bismuth, and the second material comprises at least one of air, plastic material, carbon, a composite of a thermoplastic resin with carbon-fiber reinforcement, a thermoplastic polymer, or a combination thereof. ### Claim 17 (depends on 13) A marker array for x-ray imaging, the array comprising: the Moiré marker for x-ray imaging according to claim 13; and an x-ray marker of an x-ray opaque material having a ball shape, a cuboid shape, a pyramidal shape, a disc shape, or any combination thereof. ### Claim 18 (depends on 15) The Moiré marker for x-ray imaging according to claim 15, wherein the pattern structure comprises: a third layer with a third pattern of the first material and the second material; and a fourth layer with a fourth pattern of the first material and the second material, wherein the third layer and the fourth layer are separated from each other by a second distance, wherein the second material of the third pattern and the second material of the fourth pattern have a second width between two adjacent pattern elements of the first material, wherein the second distance is larger than the second width, and a ratio of the first width to the first distance is different from a ratio of the second width to the second distance.