阅读说明：本技术 受试者的相关表面点的采样方法 (Method for sampling relevant surface points of a subject ) 是由 费迪南德·施托希 詹尼克·克里斯特 于 2020-04-09 设计创作，主要内容包括：提供了一种用于对医学导航系统的受试者的相关表面点进行采样的方法和配准设备。特别地,从受试者的多个表面点中,接受相关表面点并且丢弃非相关表面点。本发明的一个技术效果是可以改进受试者的表面几何形状获取。为此,获取表面点的附加信息,并且将附加信息分配给相应的表面点以用于验证每个表面点。(A method and a registration device for sampling relevant surface points of a subject of a medical navigation system are provided. In particular, from a plurality of surface points of the subject, relevant surface points are accepted and non-relevant surface points are discarded. A technical effect of the present invention is that surface geometry acquisition of a subject may be improved. To this end, additional information of the surface points is acquired and assigned to the respective surface points for verification of each surface point.)

1. A method of sampling relevant surface points of a subject (20) of a medical navigation system, the method comprising the steps of:

determining (S1) a surface registration type for an expected process (P) of the subject (20) from the expected process (P), wherein the surface registration type comprises at least one relevant tissue type of at least part of the subject (20);

determining (S2) a position of at least one surface point (21,22) of the subject (20) using a registration device (10);

identifying (S3) a tissue type of the subject (20) at the determined at least one surface point (21, 22); and

validating (S4) the at least one surface point (21,22) as a function of the identified tissue type and the determined surface registration type of the intended treatment (P), thereby determining the location of at least one relevant surface point (21) and/or at least one non-relevant surface point (22), wherein the at least one relevant surface point (21) is accepted and the at least one non-relevant surface point (22) is discarded.

2. The method of claim 1, wherein

Determining (S2) the position of the at least one surface point (21,22) comprises: determining a spatial position (X) and/or orientation (O) of the registration device (10) with respect to the subject (20), and determining a distance (d) between the registration device (10) and the surface point (21,22) of the subject (20).

3. The method of any one of claims 1 or 2, wherein

Identifying a tissue type of the subject (20) comprises: determining a property measure of the subject (20) and comparing the determined property measure of the subject (20) with predetermined property values associated to different tissue types.

4. The method of any one of the preceding claims, wherein

The property measurements include radiation attenuation, color, spectral absorption, raman spectroscopy, and/or fluorescence.

5. The method of any one of the preceding claims, wherein

Simultaneously for each surface point (21, 22): determining (S2) a position of at least one surface point (21,22) of the subject (20) and identifying (S3) a tissue type of the subject (20) at the determined at least one surface point (21, 22).

6. The method according to any of the preceding claims, comprising the steps of:

determining (S2) a position of the at least one surface point (21,22) of the subject (22) by using a contactless tracking device (11 a).

7. The method of claim 6, comprising the steps of:

determining (S2) a position of the at least one surface point (21,22) of the subject (22) by using an optical tracking device.

8. The method of claim 7, comprising the steps of:

determining the spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom by using at least one optical marker of the optical tracking device.

9. The method of claim 6, comprising the steps of:

determining (S2) a position of the at least one surface point (21,22) of the subject (22) by using an electromagnetic tracking device.

10. The method of claim 9, comprising the steps of:

determining the spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom by using at least one electromagnetic sensor, in particular a coil or chip, of the electromagnetic tracking device.

11. The method of claim 6, comprising the steps of:

determining (S2) a position of the at least one surface point (21,22) of the subject (22) by using a magnetic tracking device.

12. The method of claim 11, comprising the steps of:

determining the spatial position (X) and/or orientation (O) of the registration device (10) with respect to the subject (20) in at least 5 degrees of freedom by using at least one magnetic sensor, in particular a chip, of the magnetic tracking device.

13. The method of claim 6, comprising the steps of:

determining (S2) a position of the at least one surface point (21,22) of the subject (22) by using a video-based tracking device.

14. The method of claim 13, comprising the steps of:

determining the spatial position (X) and/or orientation (O) of the registration device (10) with respect to the subject (20) in at least 5 degrees of freedom by using at least one video marker of the video-based tracking device.

15. The method according to any of the preceding claims, comprising the steps of:

performing a surface matching registration based on the accepted relevant surface points (21), thereby registering the subject (20) with the medical navigation device.

16. The method of claim 15, comprising the steps of:

verifying the surface matching registration by comparing a real position of the registration device (10) with respect to the subject (20) with a virtual position of a virtual representation (30) of the registration device (10) with respect to an image dataset (40) of the subject (20).

17. The method according to any of the preceding claims, comprising the steps of:

determining a position of the at least one surface point (21,22) of the subject (20) by using a contact-based tracking device (11 b).

18. The method according to any of the preceding claims, comprising the steps of:

switching between determining the position of the at least one surface point (21,22) using the contact-based tracking device (11b) and determining the position of the at least one surface point (21,22) using the contactless tracking device (11a) in dependence on the determined distance (d) between the registration device (10) and the surface point (21,22) of the subject (20).

19. A registration device (10) for registering a subject (20) of a medical navigation system, comprising:

a tissue type identification unit (14) configured for identifying a tissue type (T) of the subject (20) at least one surface point (21, 22); and

a control device (15) configured for: determining a position of the at least one surface point (21,22) of the subject (20); determining a surface registration type (R) for an expected process (P) of the subject (20) from the expected process (P), wherein the surface registration type (R) comprises at least one relevant tissue type of at least part of the subject (20); and validating the at least one surface point (21,22) as a function of the identified tissue type (T) and the determined surface registration type (R) of the expected process (P), thereby determining a location of at least one relevant surface point (21) and/or at least one non-relevant surface point (22), wherein the at least one relevant surface point (21) is accepted and the at least one non-relevant surface point (22) is discarded.

20. The registration apparatus (10) as defined in claim 19, comprising:

a tracking device (11) configured for determining a spatial position (X) and/or orientation (O) of the registration device relative to the subject (20); and

a proximity sensor (13) configured for determining a distance (d) between the registration device (10) and at least one surface point (21,22) of the subject (20); wherein

The control device (15) is configured for determining a position of at least one surface point (21,22) of the subject (20) from the determined spatial position (X) and/or orientation (O) and/or distance (d).

21. Registration device according to any of claims 19 or 20, wherein

The tracking device (11) comprises a contactless tracking device (11a), the contactless tracking device (11a) being configured for determining a position of the at least one surface point of the subject.

22. Registration device according to claim 21, wherein

The contactless tracking device comprises an optical tracking device configured for determining a position of the at least one surface point (21,22) of the subject (20).

23. Registration device according to claim 22, wherein

The optical tracking apparatus includes:

at least one optical marker configured for determining a spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom.

24. Registration device according to claim 21, wherein

The tracking device comprises an electromagnetic tracking device configured for determining a position of the at least one surface point (21,22) of the subject (20).

25. Registration device according to claim 24, wherein

The electromagnetic tracking apparatus includes:

at least one electromagnetic sensor, in particular a coil or a chip, is configured for determining a spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom.

26. Registration device according to claim 21, wherein

The tracking device comprises a magnetic tracking device configured for determining a position of the at least one surface point (21,22) of the subject (22).

27. Registration device according to claim 26, wherein

The magnetic tracking device comprises

At least one magnetic sensor, in particular a chip, is configured for determining a spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom.

28. Registration device according to claim 21, wherein

The tracking device comprises a video-based tracking device configured for determining a position of the at least one surface point (21,22) of the subject (20).

29. Registration device according to claim 28, wherein

The video-based tracking device includes:

at least one video marker configured for determining a spatial position (X) and/or orientation (O) of the registration device (10) relative to the subject (20) in at least 5 degrees of freedom.

30. Registration device according to any of claims 19 to 29, wherein

The tracking device (11) comprises a contact-based tracking device (11b) configured for determining a position of the at least one surface point (21,22) of the subject (20).

31. Registration device according to any of claims 19 to 30, wherein

The control device (15) is configured for verifying a surface matching registration by comparing a real position of the registration device (10) with respect to the subject (20) with a virtual position of a virtual representation (30) of the registration device (10) with respect to an image dataset (40) of the subject (20).

32. Registration device according to any of claims 19 to 31, wherein

The control device (15) is configured for performing a surface matching registration based on the accepted relevant surface points (21), thereby registering the subject (20) with the medical navigation device.

33. Registration device according to any of claims 19 to 32, wherein

The control unit (15) is configured for: switching between determining the position of the at least one surface point (21,22) using the contact-based tracking device (11b) and determining the position of the at least one surface point (21,22) using the contactless tracking device (11a) in dependence on the determined distance (d) between the registration device (10) and the surface point (21,22) of the subject (20).

34. A surgical navigation system for computer-assisted surgery, the system comprising a registration apparatus according to any of claims 19 to 33.

35. A program which, when run on or loaded onto a computer, causes the computer to perform the method steps of the method according to any one of the preceding claims;

and/or a program storage medium having the program stored thereon;

and/or a computer comprising at least one processor and memory and/or the program storage medium, wherein the program is run on a computer or loaded into the memory of the computer;

and/or a signal wave or digital signal wave carrying information representative of the program;

and/or a data stream representing the program.

Technical Field

The present invention relates to a method of sampling relevant surface points of a subject of a medical navigation system, a registration device, a surgical navigation system for computer-assisted surgery and a computer program.

Background

Surface-based image registration is an established method of associating medical image data with an anatomical region of a patient. The surface geometry acquisition method can be classified into a non-contact method and a contact-based method. Contact-based methods are generally prone to measurement errors because points may be acquired above or below the actual surface. On the other hand, the contactless method cannot generally be used to acquire points on a covered (e.g. hair covered) area.

The invention can be used for IGS (image guided surgery) workflow. Potential applications include spinal surgery, skull surgery, ear, nose and throat surgery, cmf surgery, and laparoscopic surgery.

Aspects, examples, and exemplary steps of the invention and embodiments thereof are disclosed below. The different exemplary features of the invention may be combined according to the invention in any technically advantageous and feasible way.

Brief description of the invention

In view of the above described prior art, it may be seen as an object of the present invention to provide an improved method for sampling relevant surface points of a subject by analysis of a tissue type of the subject including a medical navigation system.

In the following, a brief description of specific features of the invention is given, which should not be understood as limiting the invention only to the features or combinations of features described in this section.

A method of sampling relevant surface points of a subject of a medical navigation system is proposed.

In particular, from a plurality of surface points of the subject, relevant surface points are accepted and non-relevant surface points are discarded. A technical effect of the present invention is that surface geometry acquisition of a subject may be improved.

For this purpose, additional information of the surface points is acquired and assigned to the respective surface points for verification of each surface point.

General description of the invention

In this section, a description is given of general features of the invention, for example by referring to possible embodiments of the invention.

This is achieved by the subject matter of the independent claims, wherein further embodiments are incorporated in the dependent claims and in the following description.

The described embodiments similarly relate to a method of sampling relevant surface points of a subject of a medical navigation system, a surgical navigation system for computer-assisted surgery and a computer program. Different combinations of the various embodiments may produce synergistic effects, although they may not be described in detail below. Furthermore, it should be noted that all embodiments of the present invention with respect to methods may be performed in the order of steps explicitly described herein. However, this is not necessarily the only and required order of the steps of the method. Unless explicitly stated to the contrary in the following, methods presented herein may be performed in another order of the disclosed steps without departing from the respective method embodiments.

Technical terms are used in their ordinary sense. If a certain term is to convey a specific meaning, the definition of that term will be given in the context in which it is used.

In accordance with the present disclosure, a method of sampling relevant surface points of a subject of a medical navigation system is provided. The method comprises the following steps: a surface registration type for an intended procedure of a subject is determined from the intended procedure of the subject, wherein the surface registration type includes at least one associated tissue type of at least a portion of the subject. Furthermore, a location of at least one surface point of the subject is determined using the registration device. The method further comprises identifying a tissue type of the subject at the determined at least one surface point and validating the at least one surface point according to the identified tissue type and the determined surface registration type of the expected process, thereby determining a location of at least one relevant surface point and/or at least one non-relevant surface point, wherein the at least one relevant surface point is accepted and the at least one non-relevant surface point is discarded.

In a preferred embodiment, the method is performed for each surface point. Alternatively, a plurality of surface points are determined, thus identifying the tissue type of the subject for each surface point, and then the verification step involves filtering relevant surface points from the plurality of determined surface points. In this case, a step of associating the determined surface points with the identified tissue type of the subject at the corresponding surface points is required.

In a preferred embodiment, a plurality of frames (or in other words images) are taken during the sampling process, wherein for each frame at least one surface point of the subject is determined and the tissue type of the determined surface point is identified. In case a 3D scanner or a structured light scanner is used, more than one surface point of the subject may be determined for each frame.

In a preferred embodiment, the tissue type comprises skin; a bone; different tissues, in particular biological tissues, such as blood vessels, heart tissue, liver tissue and/or kidney tissue; and/or non-biological tissue such as drapes (particularly surgical drapes), silicone incise drapes, and/or table pads. The term "tissue type" as used herein may generally relate to a surface type.

In a preferred embodiment, the surface registration types comprise facial registration (in particular for neurosurgery), intranasal registration (in particular for otorhinolaryngological surgery), liver registration (in particular for laparoscopic surgery and/or open surgery), and/or bone surface registration (in particular for spinal surgery and/or orthopaedic surgery).

Thus, for example, for facial registration and/or ear-nose-throat surgery, the relevant tissue types include skin. In another example, for bone surface registration, the relevant tissue type includes bone. According to another example, for liver registration, the relevant tissue type comprises liver tissue. For example, for intranasal registration, the relevant tissue type includes mucosa.

The term "subject" as used herein includes a human body (in particular a patient).

The term "surface point" as used herein may also be referred to as a surface coordinate.

The term "correlated surface points" as used herein relates to surface points verified as correlated to the determined surface registration type. For example, a surface point with a tissue type "bone" is a relevant surface point for spinal surgery. In another example, the surface points having the tissue type "drape" are typically non-relevant surface points.

The term "intended procedure" relates to a procedure and/or intervention, such as a surgery intended to be performed on a certain subject (e.g. a patient).

Preferably, the method as described herein relates to a computer-implemented medical method.

Thus, only relevant surface data is acquired and non-relevant surface data does not distort the relevant data set.

Thus, the surface geometry acquisition of the subject may be improved.

Computer-implemented method

The method according to the invention is for example a computer-implemented method. For example, all or only some of the steps (i.e., less than the total number of steps) of a method according to the present invention may be performed by a computer (e.g., at least one computer). An embodiment of the computer-implemented method is to use a computer to perform the data processing method. Embodiments of a computer-implemented method pertain to methods of operating a computer such that the computer is operated to perform one, more, or all of the steps of the method.

The computer for example comprises at least one processor and for example at least one memory to (technically) process data, for example electronically and/or optically. The processor is for example made of a substance or composition being a semiconductor, for example an at least partially n-doped and/or p-doped semiconductor, for example at least one of a II semiconductor material, a III semiconductor material, an IV semiconductor material, a V semiconductor material, a VI semiconductor material, for example (doped) silicon and/or gallium arsenide. The described calculation steps or determination steps are performed, for example, by a computer. The determination step or the calculation step is, for example, a step of determining data within the framework of the technical method (for example within the framework of the program). The computer is for example any type of data processing device, such as an electronic data processing device. The computer may be a device that is commonly considered a computer, such as a desktop PC, a notebook, a netbook, etc., but may also be any programmable apparatus, such as a mobile phone or an embedded processor. The computer may, for example, comprise a system (network) of "sub-computers", wherein each sub-computer itself represents a computer. The term "computer" includes a cloud computer such as a cloud server. The term "cloud computer" includes cloud computer systems, e.g., systems comprising at least one cloud computer and, for example, a plurality of cloud computers (such as server farms) operatively interconnected. Such cloud computers are preferably connected to a wide area network, such as the World Wide Web (WWW), and are located in a so-called computer cloud both connected to the world wide web. Such infrastructures are used for "cloud computing," which describes computing, software, data access and storage services that do not require end users to know the physical location and/or configuration of the computers providing a particular service. For example, the term "cloud" is used in this regard as a metaphor for the internet (world wide web). For example, the cloud provides computing infrastructure as a service (IaaS). The cloud computer may serve as a virtual host for an operating system and/or data processing applications for performing the methods of the present invention. The cloud computer is, for example, an elastic computing cloud provided by amazon Web services (EC 2). A computer for example comprises an interface for receiving data or outputting data and/or performing an analog-to-digital conversion. The data is, for example, data representing a physical property and/or generated from a technical signal. The technical signal is generated, for example, by means of a (technical) detection device (e.g., a device for detecting the marking device) and/or a (technical) analysis device (e.g., a device for performing the (medical) imaging method), wherein the technical signal is, for example, an electrical signal or an optical signal. The technical signal represents, for example, data received or output by a computer. The computer is preferably operatively coupled to a display device that enables information output by the computer to be displayed to, for example, a user. One example of a display device is a virtual reality device or augmented reality device (also referred to as virtual reality glasses or augmented reality glasses) that can be used as "goggles" for navigation. A specific example of such augmented reality glasses is google glasses (a trademark of google corporation). Augmented reality devices or virtual reality devices may be used to input information to a computer through user interaction, and may also be used to display information output by the computer. Another example of a display device would be a standard computer monitor including, for example, a liquid crystal display operatively coupled to a computer for receiving display control data from the computer to generate signals for displaying image information content on the display device. A particular embodiment of such a computer monitor is a digital light box. An example of such a digital light box is the Buzz product of bod doctor stock corporation (Buzz). The monitor may also be the monitor of a portable (e.g., handheld) device such as a smart phone or personal digital assistant or digital media player.

The invention also relates to: a program which, when run on a computer, causes the computer to perform one or more or all of the method steps described herein; and/or a program storage medium on which the program is stored (in particular in a non-transitory form); and/or a computer including the program storage medium; and/or a signal wave (e.g. a digital signal wave) (physical, e.g. electrical, e.g. generated technically) carrying information representing a program, e.g. a program as mentioned above, e.g. comprising code means adapted to perform any or all of the method steps described herein.

Within the framework of the invention, computer program elements may be embodied in hardware and/or in software (which includes firmware, resident software, micro-code, etc.). Within the framework of the invention, a computer program element may take the form of a computer program product, which can be embodied by a computer-usable, e.g., computer-readable, data storage medium comprising computer-usable, e.g., computer-readable program instructions, "code" or a "computer program" embodied in the data storage medium for use on or in connection with an instruction execution system. Such a system may be a computer; the computer may be a data processing device comprising means for executing the computer program element and/or the program according to the invention, for example a data processing device comprising: a digital processor (central processing unit or CPU) that executes a computer program unit; and an optional volatile memory, such as random access memory or RAM, for storing data used to execute the computer program element and/or data generated by execution of the computer program element. Within the framework of the present invention, a computer-usable, e.g., computer-readable, data storage medium may be any data storage medium that can store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-usable, computer-readable data storage medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a propagation medium such as the internet. The computer-usable or computer-readable data storage medium may even be, for instance, paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other suitable medium, and then compiled, interpreted, or otherwise processed in a suitable manner. The data storage medium is preferably a non-volatile data storage medium. The computer program product and any software and/or hardware described herein form the various means for carrying out the functions of the invention in the example embodiments. The computer and/or the data processing device may for example comprise a boot information device comprising means for outputting boot information. The guiding information may be output to the user, for example visually by visual indication means (e.g. a monitor and/or a light) and/or acoustically by acoustic indication means (e.g. a speaker and/or a digital voice output device) and/or by tactile indication means (e.g. a vibrating element or a vibrating element incorporated into the apparatus). For the purposes of this document, a computer is a technical computer which, for example, comprises technical components, for example tangible components, such as mechanical components and/or electronic components. Any device so mentioned in this document is a technical device, e.g. a tangible device.

Obtaining data

For example, the expression "obtaining data" (within the framework of a computer-implemented method) includes scenarios in which the data is determined by a computer-implemented method or program. Determining the data comprises, for example, measuring a physical quantity and converting the measured value into data (e.g. digital data), and/or calculating (and for example outputting) the data by means of a computer and, for example, within the framework of the method according to the invention. "acquiring data" also includes, for example, by (e.g., input to) a computer-implemented method or program, e.g., receiving data from or retrieving data from another program, a previous method step, or a data storage medium, e.g., for further processing by a computer-implemented method or program. The generation of the data to be acquired may, but need not, be part of the method according to the invention. Thus, the expression "acquiring data" may also for example mean waiting to receive data and/or receiving data. The received data may be input, for example, via an interface. The expression "obtaining data" may also mean that a computer-implemented method or program performs steps to (actively) receive or retrieve data from a data source, such as a data storage medium (e.g., ROM, RAM, a database, a hard drive, etc.), or via an interface (e.g., from another computer or a network). The data obtained by the disclosed method or apparatus, respectively, may be obtained from a database located in a data storage device operatively connected to the computer for data transfer between the database and the computer (e.g., from the database to the computer). The computer obtains the data for use as input to the step of determining the data. The determined data may again be output to the same database or another database for storage for later use. The database or databases used to implement the disclosed methods can be located on a network data storage device or a network server (e.g., a cloud data storage device or a cloud server) or a local data storage device (e.g., a mass storage device operatively connected to at least one computer that performs the disclosed methods). The data may be made "ready for use" by performing additional steps prior to the acquiring step. According to this additional step, data is generated for acquisition. The data (e.g. by the analysis device) is for example detected or captured. Alternatively or additionally, data is input (e.g. via an interface) according to an additional step. The generated data may be input (e.g., into a computer), for example. According to additional steps (prior to the obtaining step), the data may also be provided by performing the following additional steps: the data are stored in a data storage medium, such as ROM, RAM, CD and/or hard disk drive, so that the data are ready for use within the framework of the method or program according to the invention. Thus, the step of "acquiring data" may also involve instructing the device to obtain and/or provide the data to be acquired. In particular, the acquisition step does not involve invasive steps representing substantial physical disturbances to the body, requiring professional medical experience to perform, and presenting substantial health risks even when performed with the required professional care and expertise. In particular, the step of acquiring data (e.g. determining data) does not involve a surgical step, and in particular does not involve a step of treating the human or animal body with surgery or therapy. To distinguish between the different data used by the method, the data is represented (i.e., referred to as) "XY data" or the like and is defined in terms of information described by the data, which is then preferably referred to as "XY information" or the like.

Registration

When assigning image data points of an image (CT, MR, etc.) stored in a navigation system to the spatial position of each point of an actual object in space (e.g. a body part in an operating room), an n-dimensional image of the body is registered.

Image registration

Image registration is the process of transforming different data sets into one coordinate system. The data may be multiple photographs and/or data from different sensors, different times, or different viewpoints. Image registration is used for computer vision, medical imaging, and compiling and analyzing images and data from satellites. In order to be able to compare or integrate the data obtained from these different measurements, a registration is required.

Marker substance

The function of the marker is to be detected by a marker detection device (e.g. a camera or an ultrasound receiver or an analysis device such as a CT or MRI device) so that its spatial position (i.e. its spatial orientation and/or alignment) can be determined. The detection device is for example part of a navigation system. The label may be an active label. The active marker may for example emit electromagnetic radiation and/or waves which may be in the infrared, visible and/or ultraviolet spectral range. However, the marker may also be a passive marker, i.e. may, for example, reflect electromagnetic radiation in the infrared, visible and/or ultraviolet spectral range or may block x-ray radiation. For this purpose, the marker may be provided with a surface having corresponding reflective properties or may be made of metal to block X-ray radiation. The marker may also reflect and/or emit electromagnetic radiation and/or waves in the radio frequency range or at ultrasonic wavelengths. The marker preferably has a spherical shape and/or a spherical shape, and may therefore be referred to as a marker sphere; however, the marker may also assume an angular shape, for example, a cubic shape.

Marking apparatus

The marking device may be, for example, a calibration star or an indicator or a single marker or a plurality of (individual) markers, which preferably are in a predetermined spatial relationship. The marking device comprises one, two, three or more markers, wherein two or more of such markers are in a predetermined spatial relationship. The predetermined spatial relationship is known, for example, to the navigation system and is stored, for example, in a computer of the navigation system.

In another embodiment, the marking device comprises an optical pattern, for example on a two-dimensional surface. The optical pattern may comprise a plurality of geometrical shapes such as circles, rectangles and/or triangles. The optical pattern may be recognized in an image captured by the camera and the position of the marking device relative to the camera may be determined from the size of the pattern in the image, the orientation of the pattern in the image, and the distortion of the pattern in the image. This enables the relative position in up to three rotational dimensions and up to three translational dimensions to be determined from a single two-dimensional image.

The position of the marking device may be determined, for example, by a medical navigation system. If the marking device is attached to an object, such as a bone or a medical instrument, the position of the object may be determined from the position of the marking device and the relative position between the marking device and the object. Determining the relative position is also referred to as registering the marker device and the object. The marking device or object may be tracked, which means that the position of the marking device or object is determined two or more times over time.

Mark holder

A marker holder is understood to mean an attachment device for a separate marker for attaching the marker to an instrument, a part of the body and/or a holding element of a calibration star, wherein the marker can be attached such that the marker is stationary and advantageously such that the marker can be detached. The marker holder may be rod-shaped and/or cylindrical, for example. A fastening device (e.g., a latching mechanism) for the marking device may be provided at the end of the marking holder facing the marker and facilitates the placement of the marking device on the marking holder in a force-fitting and/or form-fitting manner.

Indicator device

The indicator is a rod comprising one or more (advantageously, two) markers fastened thereto and can be used to measure respective coordinates, e.g. spatial coordinates (i.e. three-dimensional coordinates), on a part of the body, wherein the user guides the indicator (e.g. the portion of the indicator having a defined and advantageously fixed position relative to at least one marker attached to the indicator) to a position corresponding to the coordinates, such that the position of the indicator can be determined by detecting the markers on the indicator using the surgical navigation system. The relative position between the marker and the indicator portion (e.g. the tip of the indicator) of the indicator for measuring coordinates is for example known. The surgical navigation system can then assign the position (in three-dimensional coordinates) to a predetermined body structure, wherein the assignment can be made automatically or by a user procedure.

Calibration star

"targeting star" refers to a device to which a plurality of markers (advantageously three markers) are attached, wherein the markers are (e.g. detachably) attached to the targeting star such that the markers are stationary, thereby providing a known (and advantageously fixed) position of the markers relative to each other. For each targeting star used within the framework of the surgical navigation method, the position of the markers relative to each other may be individually different, so that the surgical navigation system can identify the corresponding targeting star based on its position of the markers relative to each other. Thus, the object (e.g., the instrument and/or the part of the body) to which the calibration star is attached may then also be identified and/or distinguished accordingly. In surgical navigation methods, targeting stars are used to attach a plurality of markers to an object (e.g., a bone or medical instrument) to enable detection of the position of the object (i.e., its spatial position and/or alignment). Such a calibration star is characterized, for example, by the way of being attached to an object (e.g. a clamp and/or a wire) and/or a holding element ensuring the distance between the marker and the object (e.g. to facilitate visibility of the marker to the marker detection device) and/or a marker holder mechanically connected to the holding element and to which the marker can be connected.

Navigation system

The invention also relates to a navigation system for computer-assisted surgery. The navigation system preferably comprises the above mentioned computer for processing data provided according to the computer implemented method as described in any one of the embodiments described herein. The navigation system preferably comprises a detection device for detecting the position of detection points representing main points and auxiliary points, to generate detection signals and to provide the generated detection signals to the computer, so that the computer can determine absolute main point data and absolute auxiliary point data based on the received detection signals. The detection points are, for example, points on the surface of the anatomical structure, for example detected by a pointer. In this way, absolute point data may be provided to the computer. The navigation system also preferably includes a user interface for receiving the calculation results (e.g., the position of the main plane, the position of the auxiliary plane, and/or the position of the standard plane) from the computer. The user interface provides the received data as information to the user. Examples of user interfaces include a display device such as a monitor or speaker. The user interface may use any type of indication signal (e.g., a visual signal, an audio signal, and/or a vibration signal). One example of a display device is an augmented reality device (also referred to as augmented reality glasses) that can be used as so-called "goggles" for navigation. A specific example of such augmented reality glasses is google glasses (a trademark of google corporation). Augmented reality devices can be used to input information to a computer of a navigation system through user interaction, and can also be used to display information output by the computer.

The invention also relates to a navigation system for computer-assisted surgery, comprising:

a computer for processing absolute point data and relative point data;

a detection device for detecting positions of the principal point and the auxiliary point to generate absolute point data, and supplying the absolute point data to the computer;

a data interface for receiving the relative point data and providing the relative point data to a computer; and

a user interface for receiving data from a computer to provide information to a user, wherein the received data is generated by the computer based on a result of a process performed by the computer.

Surgical navigation system

A navigation system (e.g. a surgical navigation system) is understood to mean a system that may comprise: at least one marking device; a transmitter which transmits electromagnetic waves and/or radiation and/or ultrasound waves; a receiver that receives electromagnetic waves and/or radiation and/or ultrasound waves; and an electronic data processing device connected to the receiver and/or the transmitter, wherein the data processing device (e.g. a computer) comprises for example a processor (CPU) and a working memory, and advantageously a pointing device (e.g. a visual pointing device such as a monitor and/or an audio pointing device such as a loudspeaker and/or a tactile pointing device such as a vibrator) for emitting a pointing signal, and a permanent data memory, wherein the data processing device processes the navigation data forwarded to it by the receiver and may advantageously output guidance information to the user via the pointing device. The navigation data may be stored in a persistent data store and compared, for example, with data previously stored in the store.

Sign (sign)

Landmarks are defined elements of an anatomical region, and landmarks are always the same or repeated with a high degree of similarity in the same anatomical region of multiple patients. Typical landmarks are, for example, the epicondyle of the femur or the end of the transverse and/or dorsal processes of the vertebrae. A point (a principal point or an auxiliary point) may represent such a mark. Landmarks located on a characteristic anatomical structure (e.g., on a surface) of a body part may also represent the structure. The landmarks may represent the entire anatomical structure or only one point or portion of the anatomical structure. The landmarks may also be located on anatomical structures such as protruding structures, for example. An example of such an anatomical structure is the posterior iliac crest. Another example of a landmark is a landmark defined by the rim of the acetabulum (e.g., by the center of the rim). In another example, the marker represents the bottom or deepest point of the acetabulum, which is from multiple detection points. Thus, one marker may for example represent a plurality of detection points. As mentioned above, the landmarks may represent anatomical features defined based on the feature structure of the body part. Additionally, the landmarks may also represent anatomical features defined by the relative movement of two body parts, such as the center of rotation of the femur when moving relative to the acetabulum.

Scaling

Determining a position is referred to as scaling if determining a position means informing the navigation system of said position in the reference frame of the navigation system.

For example, the present invention does not relate to or specifically include or encompass invasive steps that would represent substantial physical disturbance to the body, require professional medical experience to perform, and present substantial health risks even when performed with the required professional care and expertise. For example, the present invention does not include the following steps: positioning the medical implant to secure the medical implant to the anatomical structure, or to prepare the anatomical structure for securing the medical implant thereto. More specifically, the present invention is not concerned or specifically includes or encompasses any surgical or therapeutic activity.

Preferred embodiments will be described in more detail below.

According to another exemplary embodiment of the present invention, the step of determining the position of the at least one surface point comprises determining a spatial position and/or orientation of the registration device with respect to the subject and determining a distance between the registration device and the surface point of the subject.

In a preferred embodiment, the spatial position and/or orientation of the registration device is determined in 5 or 6 degrees of freedom. Preferably, the tracking device determines the spatial position and/or orientation of the registration device relative to the subject.

Preferably, the tracking system is configured for determining the spatial position and/or orientation of the registration device and the subject, thereby determining the relation of the registration device and the spatial position and/or orientation of the subject. In other words, a reference point is determined, relative to which the spatial position and/or orientation of the registration device and the subject is determined. Thus, the spatial position and/or orientation of the registration device with respect to the subject may be determined. The tracking system preferably comprises all components necessary for tracking the registration device and the subject.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the invention, the method comprises a step of identifying a tissue type of the subject, the step comprising: the method includes determining a characteristic measure of the subject and comparing the determined characteristic measure of the subject to predetermined characteristic values associated with different tissue types.

The term property measurement relates to different properties of a subject that can be measured.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the characteristic measurement comprises radiation attenuation, color, spectral absorption, raman spectroscopy and/or fluorescence.

Preferably, the color relates to the original color of the subject, such as skin color or hair color. In addition, for example, green or blue colors are not common to human body surfaces, but are common to drapes used in medical technology. Thus, the color of the subject at a particular surface point may be indicative of the tissue type of the subject.

The property measurement is preferably measured by a tissue type identification unit, which further preferably comprises a property measurement unit configured for measuring the property measurement of the subject. The characteristic measurement unit preferably includes: camera means (in particular for measuring color), radiation detector (in particular for measuring attenuation of radiation), spectrometer (in particular for measuring spectral absorption), raman spectrometer (in particular for measuring raman spectrum), and/or photometer (in particular for measuring fluorescence).

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the steps of: at least one surface point of the subject is determined, and identifying a tissue type of the subject at the determined at least one surface point is performed simultaneously for each surface point.

Thus, the step of associating the tissue type to the corresponding surface point is not required.

Thus, the surface geometry acquisition of the subject may be simplified and thus improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the position of at least one surface point of the subject by using a contactless tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining at least one surface point of the subject by using an optical tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the spatial position and/or orientation of the registration device with respect to the subject in at least 5 degrees of freedom by using at least one optical marker of the optical tracking device.

Preferably, the tracking device is a component of the registration device for tracking the registration device.

In a preferred embodiment, the method comprises the steps of: providing a light beam by an optical light source of an optical tracking system, reflecting the light beam at least one light-reflective optical marker arranged at least at the registration device, and determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the reflected light beam.

Preferably, the light beam is an infrared light beam.

Preferably, the at least one optical marker is arranged at the registration device and the subject, respectively.

Preferably, the optical light source defines a reference point relative to which the spatial position and/or orientation of the registration device and the subject is determined.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the position of at least one surface point of the subject by using an electromagnetic tracking device.

The tracking device is for example an electromagnetic tracking device comprising at least one electromagnetic sensor (in particular a coil and/or a chip) for tracking. Preferably, the electromagnetic sensor is arranged within the tracking device at an angle to other sensors of the tracking device. In contrast to optical tracking, electromagnetic tracking does not rely on visual connection with the subject. Therefore, electromagnetic tracking is particularly preferred for tip tracking of a subject and/or flexible instrument in a prone position. This also applies if the subject is covered, in particular by a ventilated item (draft) or when the subject is stained with blood.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the spatial position and/or orientation of the registration device with respect to the subject in at least 5 degrees of freedom by using at least one electromagnetic sensor (in particular a coil or a chip) of the electromagnetic device.

In a preferred embodiment, the method comprises the steps of: providing a time-varying electromagnetic field by an electromagnetic field generator of an electromagnetic tracking system, and determining a spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the electromagnetic field. Preferably, the electromagnetic sensor is configured to detect a change in the electromagnetic field over time. For example, if the electromagnetic sensor comprises at least one coil, the time-varying electromagnetic field induces a time-varying current into the coil.

Preferably, the at least one electromagnetic sensor is arranged at the registration device and the subject, respectively.

Preferably, the electromagnetic field generator defines a reference point to which the spatial position and/or orientation of the registration device and the subject is determined.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the position of at least one surface point of the subject by using a magnetic tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the spatial position and/or orientation of the registration device with respect to the subject in at least 5 degrees of freedom by using at least one magnetic sensor of the magnetic tracking device.

In a preferred embodiment, the method comprises the steps of: providing a time-varying magnetic field by a magnetic field generator of the magnetic tracking system, and determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the magnetic field. Preferably, the magnetic sensor is configured to detect a change in the magnetic field over time.

Preferably, the magnetic field generator comprises a permanent magnet and is configured to rotate the permanent magnet simultaneously about a first axis of rotation and a second axis of rotation to generate a time-varying magnetic field. The second rotational axis intersects the first rotational axis at an intersection that is offset from the center of mass of the permanent magnet.

Preferably, the magnetic sensor comprises a giant magnetoresistive sensor, an anisotropic magnetoresistive sensor or a hall effect sensor.

Preferably, the at least one magnetic sensor is arranged at the registration device and the subject, respectively.

Preferably, the magnetic field generator defines a reference point to which the spatial position and/or orientation of the registration device and the subject is determined.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the position of at least one surface point of the subject by using a video-based tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the spatial position and/or orientation of the registration device with respect to the subject in at least 5 degrees of freedom by using at least one video marker of the video-based tracking device.

In a preferred embodiment, the method comprises the steps of: identifying, by a camera of a video-based tracking system, a video marker arranged at least at the registration device, and determining a spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the video marker.

Preferably, the videomark is a barcode or QR code.

Preferably, the at least one videomarker is arranged at the registration device and the subject, respectively.

Preferably, the camera defines a reference point to which the spatial position and/or orientation of the registration device and the subject are determined.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the steps of: performing a surface matching registration based on the accepted relevant surface points, thereby registering the subject to the medical navigation device.

In a preferred embodiment, the medical navigation device has stored virtual image data of the subject, the relevant surface points being matched with the virtual image data of the subject for surface matching registration. In addition, the medical navigation device has stored virtual image data of the registration device consistent with the tracked registration device. Thus, if the matching is performed perfectly, the arrangement of the registration device to the subject in reality coincides with the arrangement of the virtual image of the registration device to the virtual image of the subject.

Preferably, the surface matching registration is performed when a predetermined amount of relevant surface points has been accepted.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the step of verifying the surface matching registration by comparing the real position of the registration device in the view of the subject with the virtual position of the virtual representation of the registration device in the view of the image dataset of the subject.

In a preferred embodiment, the verification step is performed by a medical professional (e.g., a surgeon).

In a preferred embodiment, easily checked control points are used for verification. For example, the user compares the real position of the tip of the registration device (in particular the tip of the pen-shaped contact-based tracking device) relative to the subject with the virtual position of the tip of the virtual representation of the registration device (in particular the tip of the pen-shaped contact-based tracking device) relative to the image dataset of the subject.

The image dataset of the subject is preferably a digital model of the subject, further preferably the sampling method is predetermined.

The position of the registration device in real life is related to the position of the registration device compared to the physical anatomy of the subject, in particular the patient.

It should be clear that it is not necessary to acquire a specific surface point of the subject at a specific location, e.g. the tip of the registration device.

According to another exemplary embodiment of the present invention, the method comprises the step of determining the position of at least one surface point of the subject by using a contact based tracking device.

Preferably, the contact-based tracking device extends from the registration device in the form of a pen, the contact-based tracking device having a tip for contacting the surface of the subject.

In a preferred embodiment, the contact-based position determination is preferably used for determining further surface points. Thus, surface points can be determined by contact-based position determination, which can hardly or not be determined entirely by contactless position determination. For example, the position of the surface of the head can be determined relatively easily by contactless position determination. However, if parts of the head are covered with hairs, a contactless position determination may not be suitable. In this case, such surface points may be determined using contact-based position determination.

Preferably, the contact-based tracking device itself is capable of determining the tissue type of the subject at different surface points when contacting the subject. For example, when contacting a subject, a contact-based tracking device may differ between bone and skin.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the method comprises the steps of: switching between determining the position of the at least one surface point using the contact-based tracking device and determining the position of the at least one surface point using the contactless tracking device in dependence on the determined distance between the registration device and the surface point of the subject.

In other words, when the registration device is in point contact with the surface, the contact-based position determination is automatically used. To prevent accidental contact-based position determination, the contact-based tracking device preferably needs to be within a predetermined distance from the subject for a predetermined time before contact-based position determination is activated.

Preferably, contact of the contact-based tracking device with the surface of the subject is detected by a contact sensor. The determination of the at least one surface point of the subject is triggered if the contact sensor detects contact of the contact-based tracking device with the surface of the subject (in particular by detecting skin contact).

Thus, the surface geometry acquisition of the subject may be improved.

According to another aspect, a configuration device for registering subjects of a medical navigation system is provided. The registration apparatus includes: a tissue type identification unit configured for identifying a tissue type of the subject at the at least one surface point, and a control device configured for determining a position of the at least one surface point of the subject, thereby determining a surface registration type for an intended procedure on the subject according to the intended procedure, wherein the surface registration type comprises at least one relevant tissue type of at least a part of the subject, and validating the at least one surface point according to the identified tissue type and the determined surface registration type of the intended procedure, thereby determining a position of the at least one relevant surface point and/or the at least one non-relevant surface point, wherein the at least one relevant surface point is accepted and the at least one non-relevant surface point is discarded.

The tissue type identification unit may alternatively be configured only to collect information about the tissue type, while an additional external unit is configured for identifying the tissue type from the information collected by the tissue type identification unit.

Alternatively, the spatial position and/or orientation of the registration device may be determined by a robotic system. If proximity sensors are attached to the distal ends of the robotic actuators, the spatial position and/or orientation may be derived from the pose of the robotic system.

For example, the configuration device is implemented as a handheld device. In other examples, the registration device is implemented as an endoscope.

Preferably, the proximity sensor is a laser triangulation sensor.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, a registration apparatus includes: a tracking device configured for determining a spatial position and/or orientation of the registration device relative to the subject; and a proximity sensor configured for determining a distance between the registration device and at least one surface point of the subject. The control device is configured for determining a position of at least one surface point of the subject from the determined spatial position and/or orientation and/or distance.

Preferably, the spatial location of the proximity sensor to the tracking device is known.

According to another exemplary embodiment of the present invention, the tracking device comprises a contactless tracking device configured for determining a position of at least one surface point of the subject.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the tracking device comprises an optical tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the optical tracking device comprises at least one optical marker configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom.

Preferably, the optical tracking system comprises: an optical light source configured to provide a light beam; and at least one light-reflective marker, arranged at least at the patient, configured for reflecting the light beam of the optical light source. Thus, the at least one optical sensor is configured for determining the spatial position and/or orientation of the registration device relative to the subject based on the reflected light beam.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the tracking device comprises an electromagnetic tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the electromagnetic tracking device comprises at least one electromagnetic sensor configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom.

Preferably, the electromagnetic tracking system comprises an electromagnetic field generator configured to generate a time-varying electromagnetic field. Hence, the at least one electromagnetic sensor (preferably an array of electromagnetic sensors) is configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the electromagnetic field.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the tracking device comprises a magnetic tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the invention, the magnetic tracking device comprises at least one magnetic sensor (preferably an array of geomagnetic sensors) configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom.

Preferably, the magnetic tracking system comprises a magnetic field generator configured for generating a time-varying magnetic field. Thus, the at least one magnetic sensor is configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the magnetic field.

Preferably, the magnetic field generator comprises a permanent magnet and is configured to rotate the permanent magnet simultaneously about the first and second axes of rotation. The second rotational axis intersects the first rotational axis at an intersection that is offset from the center of mass of the permanent magnet.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the tracking device comprises a video-based tracking device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the video-based tracking device comprises at least one video sensor configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom.

Preferably, the video-based tracking system comprises at least one scannable marker arranged at the registration device. Thus, the at least one video sensor is configured for determining the spatial position and/or orientation of the registration device relative to the subject in at least 5 degrees of freedom based on the scannable marker.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the electromagnetic tracking device comprises at least one sensor (in particular a coil and/or a chip) configured for determining the spatial position of the registration device with respect to the subject in at least 5 degrees of freedom.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the invention, the tracking device comprises a contact-based tracking device, preferably an indicator, further preferably the tracking device comprises in addition to the contactless tracking device a contact-based tracking device configured for determining the position of at least one surface point of the subject.

The contact-based tracking device preferably includes a soft contact.

In a preferred embodiment, the contact-based tracking device is configured for identifying the tissue type of the determined at least one surface point.

Thus, a tracking registration device is provided having means for contactless tracking and contact based tracking.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the invention, the control device is configured for verifying the surface matching registration by comparing a real position of the registration device relative to the subject with a virtual position of the virtual representation of the registration device relative to the image dataset of the subject.

Preferably, the surface matching registration is automatically verified. Preferably, after the matching process is completed, the subject is contacted with a contact-based tracking device for verification. In one embodiment, the verification of the surface matching registration is based on a measured pressure applied to the tip of the contact based tracking device. In the case where the virtual representation of the registration device meets at the contact point relative to the virtual location of the image dataset of the subject, the pressure applied to the tip of the contact-based tracking device is determined. It is desirable for the tip of the contact-based tracking device to be in contact with the subject when the surface matching registration is accurate. Thus, a slight force or pressure should be measurable at the end of the contact-based tracking device.

Thus, the measured pressure applied to the tip of the contact based tracking device is compared to a predetermined force range (preferably to the lower boundary of zero). If it is determined that no force is applied to the tip of the contact-based tracking device, or in other words, the contact-based tracking device is not in contact with the subject in real life, then the surface matching registration is not automatically verified. If it is determined that a force greater than the force range is applied to the end of the contact-based tracking device, or in other words, the contact-based tracking device is not only in contact with the subject, but is pressed onto the subject's skin in real life, then surface matching registration is not verified. However, verification is preferably required. Thus, if it is determined that the force measured at the tip of the contact based tracking device is within a predetermined force range, the surface matching registration is automatically verified.

In other words, the control device is configured for: determining a force applied to a tip of a contact based tracking device; determining that the virtual representation of the registration device meets at the contact point relative to a virtual position of the image dataset of the subject; comparing a force applied to the tip of the contact based tracking device to a predetermined force range; and verifying that the surface matches registration if the determined force is within the force range and not verifying that the surface matches registration if the determined force is not within the force range.

In addition, the control device preferably checks a predetermined minimum amount of time to hold the registration device in the position to be verified and a predetermined minimum amount of comparison contact points before verifying or not verifying that the surfaces match the registration.

Alternatively, a medical professional (e.g., surgeon) verifies the surface matching registration. In this case, it is also preferred that the registration device only allows manual verification by a medical professional if the contact-based tracking device is determined to be in contact with the subject in real life, for example by determining that a force is applied to the tip of the contact-based tracking device as a result of keeping the contact-based tracking device in contact with the subject in real life.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the present invention, the control device is configured for performing a surface matching registration based on the accepted relevant surface points, thereby registering the subject with the medical navigation device.

Thus, the surface geometry acquisition of the subject may be improved.

According to another exemplary embodiment of the invention, the control unit is configured for: switching between determining the position of the at least one surface point using the contact-based tracking device and determining the position of the at least one surface point using the contactless tracking device in dependence on the determined distance between the registration device and the surface point of the subject.

Thus, the surface geometry acquisition of the subject may be improved.

According to another aspect of the present invention, there is provided a surgical navigation system for computer-assisted surgery, the system comprising a registration apparatus as described herein.

According to the present disclosure, a computer program is provided which, when run on a computer or loaded onto a computer, causes the computer to perform the method steps of the method as described herein. Further, a program storage medium having the program stored thereon is provided. Furthermore, a computer comprising at least one processor and a memory and/or a program storage medium is provided, wherein the program is run on the computer or is loaded into the memory of the computer. There is provided a signal wave or a digital signal wave carrying information representing a program. A data stream representing a program is provided.

Such as the above mentioned program, for example comprising code means adapted to perform any or all of the steps of the method according to the first aspect. The computer program stored on the disc is a data file and when the file is read and transmitted, the file becomes a data stream, for example in the form of a signal (physical, e.g. electrical, e.g. technically generated). The signal may be implemented as a signal wave as described herein. For example, signals (e.g., signal waves) are configured to be transmitted via a computer network (e.g., LAN, WLAN, WAN, e.g., internet). The invention according to the second aspect may therefore alternatively or additionally relate to a data stream representing the above mentioned program.

In another aspect, the invention relates to a non-transitory computer readable program storage medium having stored thereon a program as described herein.

Drawings

The present invention is described hereinafter with reference to the accompanying drawings, which give a background description and which show specific embodiments of the invention. The scope of the invention, however, is not limited to the specific features disclosed in the context of the drawings, in which

FIG. 1 schematically shows a flow chart of an embodiment of the method of the present invention;

fig. 2 schematically shows a registration device arranged in front of a subject;

fig. 3 schematically shows a virtual representation of a registration device arranged in front of an image dataset of a subject;

FIG. 4 schematically shows a flow chart of an embodiment of the method of the present invention; and

fig. 5 schematically shows a registration device.

Detailed Description

Fig. 1 schematically shows a flow chart of an embodiment of a method of sampling relevant surface points of a subject 20 of a medical navigation system. In step Z1, a surface registration type R for the prospective procedure P is determined based on the prospective procedure P of the subject. For example, the desired procedure P is neurosurgery. Therefore, the surface registration type R is determined as face registration.

In step Z2, the user (in particular a medical expert) aims at the registration device 10 for registering the subject 20 at the subject 20. In this case, the subject 20 is the anatomy of a patient. At the beginning, a contactless point acquisition process is performed to determine the position of a plurality of surface points 21,22 of the subject 20. The determination of the surface points 21,22 is performed, for example, by continuous measurements, preferably as long as the user presses a button on the registration device 10. The measurement process determines a plurality of frames of subject 20.

In step Z3, for each frame determined, the following measurements are performed. First, the spatial position X and/or orientation O of the registration device 10 relative to the subject 20 is determined. Preferably, the spatial position X and/or orientation O is determined in 5 to 6 degrees of freedom. Secondly, the distance d between the registration device 10 and the measured surface points 21,22 on the subject 20 is determined. Again, a measurable property (referred to as a property measurement) of the subject's surface, in particular of each surface point 21,22 measured, is determined. For example, the color of the subject 20 at a particular surface point 21,22 is a measure of the characteristics of this. In this case, the measurable characteristic is measured by an image pickup device (not shown).

In step Z4, the surface points 21,22 (in particular the surface coordinates) are calculated by combining the spatial position X and/or orientation O of the registration device 10 with the distance d of the registration device 10 to the subject 20.

In step Z5, a tissue type T of the subject's surface is determined for each of the measured surface points 21,22 based on the determined characteristic measurements. For example, if the measured surface points 21,22 are associated with a green characteristic measurement, the identified tissue type T is a surgical drape. Such an association is preferably performed based on comparing the value of the measured property measurement with values of property measurements known to have been stored in association.

In step Z6, the surface points 21,22 are linked to the tissue type T determined on the basis of the characteristic measurements associated with the surface points 21, 22.

In step Z7, the surface points 21,22 are verified. According to the expected process P (in particular the determined registration type R), non-relevant surface points 22 that are considered not relevant to the expected process P are discarded and relevant surface points that are considered relevant to the expected process P are accepted. For example, in the case where the intended procedure P is a neurosurgery, the surface registration type R is determined as the facial registration. Thus, the relevant tissue type is skin. Based on the measured color of the surface points 21,22, one of the surface points 21,22 having a skin color is associated with the tissue type skin and is thus determined as the relevant surface point 21. The other of the surface points 21,22 is associated with a brown colour. Thus, the tissue type T of the surface point is determined as a hair that is not related to the intended process P. Such surface points are considered to be non-relevant surface points 22 and are discarded.

In step Z8, it is determined whether additional surface points 21,22 are needed to better acquire the subject 20. If more surface points 21,22 are required, the method jumps to step Z9. Otherwise, the method jumps to step Z10.

In step Z9, additional surface points 21,22 are acquired by means of contact-based point acquisition. In this case, the area of the patient's face covered by hairs can be circumvented by contact-based point acquisition and is therefore directly determined. The measurement of the surface points 21,22 is triggered manually, for example by pressing a button on the registration device 10 and/or automatically by tissue contact.

In step Z10, surface matching registration is performed, thereby registering the subject 20 with the medical navigation device. The medical navigation device has stored an image dataset 40 of the subject 20 as a virtual representation of the subject 20. The image data set 40 is matched to the measured relevant surface points 21. Thus, the registration device 10 tracked by the tracking devices 11a, 11b is matched to the virtual representation 30 of the registration device.

In step Z11, surface matching registration is verified. The position of the registration device 10 is compared with the position of the virtual representation 30 of the registration device relative to the image data set 40. For example, the tip 12 of the registration device 10 is held against the tip of the nose of the subject 20. Ideally, the virtual representation 30 of the registration device is in contact with the tip of the nose in the image dataset 40. The user may then determine whether the matching process is accurate enough for the intended process P.

Fig. 2 schematically shows the registration device 10 arranged in front of a subject 20. The subject 20 is a head 23 of a patient having hair 24. The head 23 of the subject 20 should be sampled for use in a medical navigation system.

Thus, the registration apparatus 10 is used. The registration device 10 comprises a tracking device 11, a proximity sensor 13, a control device (not shown) and a tissue type identification unit (not shown).

The tracking device 11 comprises a contactless tracking device 11a, which in this case is an electromagnetic tracking device with at least one coil C1, and a contact-based tracking device 11b, which in this case is a pen-shaped pointer with at least one coil C2. The coils C1, C2 allow five free point tracking, in other words, allow the determination of the spatial position X and/or orientation O of the registration device 10. The contact based tracking device 11b includes a tip 12.

The proximity sensor 13 comprises a laser 13a and a CCD sensor 13b, the proximity sensor 13 being configured for determining the distance d between the registration device 10 and the different surface points 21,22 of the subject 20.

It can be seen that surface points associated with the hair 24 may be considered non-associated surface points 22 and should not be considered during sampling of the associated surface of the subject 20. On the other hand, the surface points related to the head 23 should be considered as the relevant surface points 21 and should be considered during the sampling of the relevant surface of the subject 20.

Fig. 3 schematically shows a virtual representation 30 of the registration device 10 arranged in front of an image dataset 40 of a subject 20. The representation is consistent with data stored in the medical navigation system. In contrast to a real subject 20 with a head 23 and a hair 24, the image dataset 40 of the subject 20 only comprises information related to the expected process P (in this case the head 23). Ideally, the sample of the subject 20 comprises only relevant surface points 21 of the subject 20. Therefore, the accuracy of surface matching registration can be improved.

To verify surface matching registration, the position of the tip 32 of the representation 30 of the registration device 10 compared to the position of the stored image dataset 40 should coincide with the position of the tip 12 of the registration device 10 compared to the position of the subject 20.

Fig. 4 schematically shows a flow chart of a method of sampling relevant surface points of a subject 20 for a medical navigation system. The method comprises a step S1 for determining a surface registration type for an intended procedure on the subject according to the intended procedure, wherein the surface registration type comprises at least one relevant tissue type of at least part of the subject. In step S2, at least one surface point 21,22 of the subject 20 is determined using the registration device 10. Next, in step S3, the tissue type of the subject 20 is identified at the determined at least one surface point 21, 22. In step S4, the at least one surface point 21,22 is verified based on the identified tissue type and the determined surface registration type of the intended procedure, thereby determining the location of the at least one relevant surface point 21 and/or the at least one non-relevant surface point 22, wherein the at least one relevant surface point 21 is accepted and the at least one non-relevant surface point 22 is discarded.

Fig. 5 schematically shows the registration device 10. The registration device 10 for registering a subject 20 of a medical navigation system comprises a tracking device 11, a proximity sensor 13, a tissue type identification unit 14 and a control device 15.

The tracking device 11 is configured for determining a spatial position X and/or orientation O of the registration device relative to the subject 20 and for providing the spatial position X and/or orientation O to the control device 15. The proximity sensor 13 is configured for determining a distance d between the registration device 10 and at least one surface point 21,22 of the subject 20 and for providing the distance d to the control device 15. The tissue type identification unit 14 is configured for identifying a tissue type T of the subject 20 at the at least one surface point 21,22 and for providing the tissue type T to the control device 15. In addition, the control device 15 is provided with an intended procedure P, in other words an intervention is planned to be performed on the subject 20 and medical navigation thereof is required.

The control device 15 is configured to: determining the position of at least one surface point 21,22 of the subject 20 from the determined spatial position X and/or orientation O and/or distance d, determining a surface registration type R for the expected process P on the subject 20 from the expected process P (wherein the surface registration type R comprises at least one relevant tissue type of at least part of the subject 20), and validating the at least one surface point 21,22 from the identified tissue type T and the determined surface registration type R of the expected process P, thereby determining the position of the at least one relevant surface point 21 and/or the at least one non-relevant surface point 22, wherein the at least one relevant surface point 21 is accepted and the at least one non-relevant surface point 22 is discarded.

The control device 15 preferably comprises a determination unit 15a and a decision unit 15 b. The determination unit 15a is configured to: determining at least one surface point 21,22 of the subject 20 from the determined spatial position X and/or orientation O and/or distance d, determining a surface registration type R for the expected process P from the expected process P of the subject 20. Thus, the determination unit 15a provides the tissue type T, the at least one surface point 21,22 and the registration type R to the decision unit 15 b. The decision unit 15b is configured for validating at least one surface point 21,22 depending on the identified tissue type T and the determined surface registration type R of the expected procedure P, thereby determining the location of at least one relevant surface point 21 and/or at least one non-relevant surface point 22, wherein at least one relevant surface point 21 is accepted and at least one non-relevant surface point 22 is discarded.