Tracker with switchable radiation characteristics

Abstract

A tracker, a surgical navigation system having the tracker, and a method of operating the tracker are described. The tracker includes a first switch configured to be operated between a first switch configuration and a second switch configuration. The tracker also includes one or more electromagnetic radiation sources configured to selectively emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic. The tracker also includes a circuit configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having the first radiation characteristic in the first switch configuration and to emit electromagnetic radiation having the second radiation characteristic in the second switch configuration, wherein the second radiation characteristic is different from the first radiation characteristic.

Description

Technical Field

[0001] The present disclosure relates generally to trackers, for example in the context of surgical navigation. In particular, a tracker having switchable radiation characteristics, a surgical navigation system including the tracker, and a method of operating the tracker are described. Background Art

[0002] Surgical navigation systems are typically configured to track a surgical object, such as a surgical instrument or a patient. Common tracking techniques involve a tracker having an electromagnetic radiation source and an optical sensor capable of detecting the electromagnetic radiation emitted by the tracker. Based on the detected electromagnetic radiation, information about one or both of the position and orientation of the tracker can be determined.

[0003] During a surgical procedure, the surgeon may want to communicate with the surgical navigation system, but a typical user interface such as a keyboard and mouse may be arranged at an inconvenient distance or in an inconvenient location. In addition, such user interfaces pose a risk of contamination to the sterile surgical environment. In particular, communicating with the surgical navigation system to calibrate or operate the tracker may be time consuming and result in contamination of the sterile surgical environment.

[0004] The surgeon can sterilize his or her hands after having operated the user interface. However, this sterilization process is time inefficient and laborious. Summary of the invention

[0005] What is needed is a technique that addresses one or more of the above or other problems.

[0006] According to a first aspect, a tracker for a surgical navigation system is provided. The tracker includes a first switch configured to be operated between a first switch configuration and a second switch configuration. The tracker includes one or more electromagnetic radiation sources configured to selectively emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic. The tracker also includes a circuit configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having the first radiation characteristic in the first switch configuration and to emit electromagnetic radiation having the second radiation characteristic in the second switch configuration, wherein the second radiation characteristic is different from the first radiation characteristic.

[0007] The first switch may be configured to be operated when the surgical navigation system is tracking the tracker. The first switch may be configured to be operated when the tracker is configured (eg, assembled) in preparation for a surgical procedure. The first switch may be user operable.

[0008] The first switch or any other switch may be configured to be operated between more than two switch configurations, such as three, four, five, six or more switch configurations. In this case, one of the switch configurations may be configured to shut down the tracker (e.g., shut down a power supply integrated into the tracker).

[0009] The electromagnetic radiation source may be configured to emit electromagnetic radiation having more than two radiation characteristics, for example two, three, four, five or more radiation characteristics.

[0010] The electromagnetic radiation source can be a light emitting diode (LED), a polymer light emitting diode, a laser, an incandescent bulb, or a fiber optic cable coupled to a light source (e.g., at its end or side). The electromagnetic radiation source can be configured to emit electromagnetic radiation in at least one of the visible spectrum, infrared spectrum, and ultraviolet spectrum.

[0011] The first radiation characteristic may include emitting electromagnetic radiation at a first operating frequency, and the second radiation characteristic may include emitting electromagnetic radiation at a second operating frequency different from the first operating frequency. The first and second operating frequencies may each indicate a rate at which the periodic intensity of the electromagnetic radiation changes. The intensity of the electromagnetic radiation may vary between a first intensity and a second intensity less than the first intensity. The second intensity may be zero or substantially zero. One of the first operating frequency and the second operating frequency may be zero, wherein the electromagnetic radiation is emitted continuously.

[0012] The first radiation characteristic may include emitting electromagnetic radiation having a first wavelength, and the second radiation characteristic may include emitting electromagnetic radiation having a second wavelength different from the first wavelength. The first and second wavelengths may be in the visible spectrum. Alternatively, the first and second wavelengths may be in the infrared spectrum. Further alternatively, one of the first and second wavelengths may be in the visible spectrum and the other of the first and second wavelengths may be in the infrared spectrum.

[0013] The tracker may include multiple electromagnetic radiation sources, for example, two, three, four, five or more electromagnetic radiation sources. In this case, the change between the first and second radiation characteristics of the multiple electromagnetic radiation sources may include at least one of the following: (i) at least one electromagnetic radiation source starts emitting electromagnetic radiation and (ii) at least one electromagnetic radiation source stops emitting electromagnetic radiation. The first subset of electromagnetic radiation sources may include exactly two electromagnetic radiation sources. In some embodiments, in the first radiation characteristic, only one source in the first subset is configured to emit electromagnetic radiation, and in the second radiation characteristic, only another source in the first subset is configured to emit electromagnetic radiation.

[0014] In the case where the tracker includes a plurality of electromagnetic radiation sources as described above, the second switch can be configured to operate between a third switch configuration and a fourth switch configuration. A first subset of the plurality of electromagnetic radiation sources can be assigned to the first switch, and a second subset of the plurality of electromagnetic radiation sources can be assigned to the second switch. The first subset of the plurality of electromagnetic radiation sources can be configured to selectively emit electromagnetic radiation having a first partial radiation characteristic or a second partial radiation characteristic. The second subset of the plurality of electromagnetic radiation sources can be configured to selectively emit electromagnetic radiation having a third partial radiation characteristic or a fourth partial radiation characteristic. The first and second switches can be configured to be operated to change only a portion of the radiation characteristics of each assigned subset of the electromagnetic radiation sources.

[0015] The tracker may include an indicator configured to provide a first indication in a first switch configuration and a second indication in a second switch configuration. The first and second indications may be at least one of: optically distinguishable and tactilely distinguishable to a user. The one or more electromagnetic radiation sources may be specifically configured to emit infrared radiation. The indicator may include an indicator light source configured to emit visible light perceptible to the human eye. The indicator may include a switch position indicator configured to assign a first position of the first switch to the first switch configuration and a second position of the first switch to the second switch configuration.

[0016] The first switch may be preconfigured to adopt a first switch configuration and adapted to switch from the first switch configuration to a second switch configuration only for a duration while the first switch is operated or for a fixed duration after the first switch is operated. The first switch may be a spring biased switch (e.g., a push button switch).

[0017] The tracker may include at least one power supply component configured to provide power to one or more electromagnetic radiation sources, such as a power supply (e.g., one or more button batteries) and / or a wireless power receiving device. The power supply may include two, three, four or more button batteries. The power supply may include CR2032 and / or CR2025 type button batteries.

[0018] The tracker may include one or more passive tracking elements configured to reflect electromagnetic radiation. The tracker may include two, three, four, five, six or more passive tracking elements. One or more passive tracking elements may be configured to reflect primarily visible light or infrared light. One or more passive tracking elements may include a reflective ball.

[0019] The tracker may have more than two switch configurations. In some variations, one or more electromagnetic radiation sources may be configured to selectively emit electromagnetic radiation having a number of radiation characteristics at least equal to the number of switch configurations, wherein each of the switch configurations may be assigned to one of the radiation characteristics. For example, the tracker may have three switch configurations, each of which is assigned to one of the three radiation characteristics, or the tracker may have four switch configurations, each of which is assigned to one of the four radiation characteristics.

[0020] The first switch (and / or, optionally, the second switch) may include a mechanical switch configured to be operated by a user (e.g., while the tracker is being tracked). The mechanical switch may include one or more elements that can be moved by the user to change the switch configuration. The switch may include a button. The switch may include a sliding portion configured to slide parallel to a surface of the tracker.

[0021] The first switch may include a first switch portion, a second switch portion configured to be electrically coupled to the first switch portion, and a third switch portion configured to be electrically coupled to the first switch portion. In some variations, the first switch is in the first switch configuration when the second switch portion is electrically coupled to the first switch portion, and the first switch is in the second switch configuration when the third switch portion is electrically coupled to the first switch portion.

[0022] The tracker may include a first tracker component and at least one second tracker component, the at least one second tracker component being at least one of movable relative to the first tracker component and removable from the first tracker component, wherein the first switch portion is provided at the first tracker component, and the second switch portion and the third switch portion are provided jointly or individually at the at least one second tracker component. As an example, the second switch portion may be provided at one second tracker component, and the third switch portion may be provided at another second tracker component. Alternatively, both the second and third switch portions may be provided at a single second tracker component. The first tracker component and the dedicated second tracker component may be configured to selectively adopt a first relative position to achieve a first switch configuration and adopt a second relative position to achieve a second switch configuration. The different relative positions may be defined by one or both of a rotational relative position and a translational relative position.

[0023] One of the first tracker component and the at least one second tracker component may carry one or more electromagnetic radiation sources. The other of the first tracker component and the at least one second tracker component may include an interface for coupling the tracker to an object to be tracked.

[0024] According to a second aspect, a surgical navigation system is provided. The surgical navigation system includes a tracker as described herein and an optical sensor capable of detecting different radiation characteristics of the tracker. The surgical navigation system also includes a processor configured to selectively identify a first switch configuration or a second switch configuration based on the radiation characteristics detected by the optical sensor.

[0025] The processor may be configured to selectively identify the first or second switch configuration based on a comparison between the detected radiation characteristic and a predetermined radiation characteristic.

[0026] The processor may be configured to assign a first tracking mode to a first switch configuration and a second tracking mode to a second switch configuration. The first and / or second tracking modes may be assigned to an instrument and / or a patient. The first and / or second tracking modes may be assigned to different body parts of a patient.

[0027] The processor may be configured to identify a switch between the first switch configuration and the second switch configuration. The processor may be configured to determine a command issued by the user based on the identified switch between the first switch configuration and the second switch configuration. The processor may be configured to control the navigation process based on the command so determined.

[0028] The optical sensor may be a camera, such as a mono camera or a stereo camera. Where the first radiation characteristic comprises emitting electromagnetic radiation at a first operating frequency and the second radiation characteristic comprises emitting electromagnetic radiation at a second operating frequency different from the first operating frequency as described above, the optical sensor may be a camera having a frame rate at least twice as high as the larger of the first and second operating frequencies of the tracker, or a camera having a frame rate at least twice as high as the larger of the first and second operating frequencies of the tracker.

[0029] Where the tracker comprises one or more passive tracking elements configured to reflect electromagnetic radiation, the optical sensor may be configured to detect electromagnetic radiation reflected by the one or more passive tracking elements.

[0030] According to a third aspect, a method for operating a tracker for a surgical navigation system is provided. The tracker includes a first switch configured to be operated between a first switch configuration and a second switch configuration, one or more electromagnetic radiation sources, and a circuit configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic, wherein the second radiation characteristic is different from the first radiation characteristic. The method may include providing power to the one or more electromagnetic radiation sources. The method also includes emitting electromagnetic radiation having the first radiation characteristic under the first switch configuration and emitting electromagnetic radiation having the second radiation characteristic under the second switch configuration by the one or more electromagnetic radiation sources.

[0031] According to a fourth aspect, a computer program product is provided, wherein the computer program product comprises a program code portion, which is configured to perform the method described herein when executed by a processor. The computer program product may be stored on a computer readable recording medium. The computer readable recording medium may be a non-transitory recording medium, such as a hard drive, a USB stick or an optical disk. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments in conjunction with the accompanying drawings, in which:

[0033] Figure 1 An embodiment of a surgical navigation system including a processor, an optical sensor, and a tracker is shown;

[0034] Figure 2A showing a perspective view of an embodiment of a tracker in a first switch configuration;

[0035] Figure 2B Shows Figure 2A A perspective view of the tracker shown in a second switch configuration;

[0036] Figure 3A An embodiment of a tracker having three passive tracking elements in a first switching configuration is shown;

[0037] Figure 3B shows the second switch configuration. Figure 3A Tracker;

[0038] Figure 4A An embodiment of a tracker having a first switch including a first switch portion, a second switch portion, and a third switch portion is shown;

[0039] Figure 4B showing a first switch portion electrically coupled to a second switch portion;

[0040] Figure 4Cshowing a first switch portion electrically coupled to a third switch portion;

[0041] Figure 5 A flow chart illustrating an embodiment of a method for operating a tracker as described herein;

[0042] Fig. 6A shows a tracker having three switch configurations, each switch configuration being assigned to one of three radiation characteristics, wherein the switch is in a first switch configuration of the three switch configurations;

[0043] Figure 6B Shows Fig. 6A The tracker shown, wherein the first switch is in a second switch configuration of the three switch configurations;

[0044] Figure 6C Shows Fig. 6A The tracker shown, wherein the first switch is in a third switch configuration of the three switch configurations;

[0045] Fig.6D A tracker having three switch configurations is shown, wherein a first switch is in a first switch configuration assigned to a first radiation characteristic;

[0046] Fig. 6E Shows Fig.6D The tracker shown, wherein the first switch is in a second switch configuration assigned to a second radiation characteristic;

[0047] Fig. 6F Shows Fig.6D The tracker shown, wherein the first switch is a third switch configuration configured to turn off the tracker;

[0048] Fig. 7A An embodiment of a tracker having a plurality of indicators that provide a first indication in a first switch configuration is shown;

[0049] Figure 7B Shows Fig. 7A The tracker shown, wherein the plurality of indicators provide a second indication in a second switch configuration;

[0050] Fig. 8A showing the intensity of electromagnetic radiation at a first operating frequency;

[0051] Figure 8B showing an intensity of electromagnetic radiation at a first operating frequency, wherein the intensity alternates between zero and an intensity greater than zero;

[0052] Figure 8C shows a change in the intensity of electromagnetic radiation from a first operating frequency to a second operating frequency;

[0053] Fig.8D showing a first change in intensity of electromagnetic radiation from a first operating frequency to a second operating frequency, followed by a second change in intensity back to the first operating frequency;

[0054] Fig. 8E shows the intensity of electromagnetic radiation during continuous emission;

[0055] Fig. 9A An embodiment of a tracker having multiple electromagnetic radiation sources is shown;

[0056] Fig. 9B Shows Fig. 9A The tracker as shown, wherein the electromagnetic radiation source stops, continues or starts emitting electromagnetic radiation;

[0057] Fig. 10A Another embodiment of a tracker is shown, wherein three of the eight electromagnetic radiation sources emit electromagnetic radiation;

[0058] Fig. 10B Shows Fig. 10A The tracker shown, wherein all electromagnetic radiation sources emit electromagnetic radiation;

[0059] Fig.11A An embodiment of a tracker having a first switch and a second switch, emitting a first radiation characteristic is shown;

[0060] Fig. 11B shows the emission of the second radiation characteristic Fig.11A The tracker shown;

[0061] Fig. 11C shows the emission of the third radiation characteristic Fig.11A The tracker shown;

[0062] Fig.11D shows the emission characteristics of the fourth radiation Fig.11A The tracker shown;

[0063] Fig. 12A An embodiment of a tracker having four subsets of electromagnetic radiation sources and four switches is shown; and

[0064] Fig. 12B An embodiment of a tracker having four subsets, each subset having four electromagnetic radiation sources, is shown. DETAILED DESCRIPTION

[0065] The tracker described herein can be used for any tracking technology involving the emission of electromagnetic radiation, such as motion capture technology and tracking of virtual reality headsets. In the following, the tracker is described in the context of a surgical navigation system, but it should be understood that the tracker is not limited thereto.

[0066] Figure 1 A surgical navigation system 10 is schematically shown and includes a processor 12, an optical sensor 14, and a tracker 16. The processor 12 is provided by a computer system 18. Alternatively, the processor 12 may be provided by a remote server or cloud computing resource.

[0067] The optical sensor 14 may be or may include a camera. The optical sensor 14 is configured to detect visible light and infrared light. Alternatively, the optical sensor 14 is configured to detect at least one of visible light, infrared light, and ultraviolet light or any combination of at least one.

[0068] The tracker 16 includes a mechanical interface for coupling to a surgical subject. Figure 1 The tracker 16 is shown coupled to a surgical object 20 in the form of a skin area around the patient's tibia. Alternatively, the tracker 16 may be coupled to other areas of the patient, such as directly to a bone (e.g., the tibia) or to an external element coupled to the patient (e.g., a table on which the patient is placed).

[0069] Figure 2A A perspective view of the tracker 16 is shown in schematic form. The tracker 16 includes at least one electromagnetic radiation source 22. For example, a single electromagnetic radiation source 22 can be used to track a surgical instrument having only two degrees of freedom of motion. In another implementation, multiple trackers 16, each having a single electromagnetic radiation source 22, can be individually coupled to multiple vertebrae of the patient in order to track deformation of the spine. In other embodiments, the tracker may include multiple electromagnetic radiation sources 22, such as two, three, four, or more. The tracker 16 may specifically include three or four (or more) such sources 22, so that the navigation system 10 can determine one or both of the position and orientation of the tracker 16 in a coordinate system (e.g., of the optical sensor 14).

[0070] Figure 2A The electromagnetic radiation source 22 shown is a light emitting diode (LED). Alternatively, the electromagnetic radiation source 22 may be any other source capable of emitting electromagnetic radiation, such as an organic light emitting diode, a polymer light emitting diode, a laser, an incandescent light bulb, or a fiber optic cable coupled to an electromagnetic radiation emitter. The electromagnetic radiation source 22 may be configured to emit electromagnetic radiation in the visible spectrum and / or the infrared spectrum. Figure 1 The optical sensor 14 is configured to detect at least a portion of a spectrum of electromagnetic radiation emitted by the electromagnetic radiation source 22 .

[0071] Tracker 16 may be tracked based on one or both of electromagnetic radiation 24 emitted by one or more electromagnetic radiation sources 22 and electromagnetic radiation reflected by one or more passive tracking elements. Thus, in some embodiments, tracker 16 may include one or more passive tracking elements configured to reflect electromagnetic radiation. Figure 3A , Figure 3B A variation of the tracker 16 is shown having three passive tracking elements 27A-27C, the tracker 16 may include any other number of passive tracking elements 27, such as one, two, four or more passive tracking elements 27. Each of the three passive tracking elements 27A-27C includes a sphere configured to reflect electromagnetic radiation. The sphere may be configured to primarily or completely reflect a particular spectrum of light, such as visible light, infrared light, or ultraviolet light.

[0072] The one or more electromagnetic radiation sources 22 may be configured to emit electromagnetic radiation such that the passive tracking element 27 is reflective (e.g., a reflectivity greater than 0.5, 0.7, or 0.9) to the spectrum of the electromagnetic radiation (e.g., infrared light or visible light). Therefore, the tracker 16 may be tracked based on the electromagnetic radiation originating from the electromagnetic radiation source 22 and the passive tracking element 27. Alternatively, the one or more electromagnetic radiation sources 22 may be configured to emit electromagnetic radiation such that the passive tracking element 27 is not reflective or is less reflective (e.g., a reflectivity less than 0.1, 0.3, or 0.5) to the spectrum of the electromagnetic radiation (e.g., infrared light or visible light). For such a tracker 16, reflections of the electromagnetic radiation source 22 by the passive tracking element 27 are reduced, which may negatively affect tracking.

[0073] Tracker 16 also includes a power source 30 configured to provide power to electromagnetic radiation source 22 . Figure 2A The power source 30 shown is a battery in the form of a button cell (e.g., a CR2032 or CR2025 button cell). Alternatively, the battery may be an AA or AAA type battery. A tracker 16 with a smaller battery (e.g., a button cell) has a smaller weight. A tracker 16 with a larger battery typically has a larger capacity for longer operating times. The power source 30 may be a rechargeable battery, such as a lithium-ion battery. The power source 30 may include a single battery or multiple batteries, such as two, three, four or more batteries. Alternatively or additionally, the power source 30 may include a power cord (e.g., connected to an electrical outlet or an outlet of a nearby surgical device). In the event that a wireless power receiving device is provided, the tracker 16 will be configured to receive power wirelessly.

[0074] Tracker 16 includes a first switch 32 configured to be activated by a user in a manner such as Figure 2A The first switch configuration 34 shown and the Figure 2B The second switch configuration 36 shown operates between.

[0075] The electromagnetic radiation source 22 is configured to selectively emit electromagnetic radiation 24 having a first radiation characteristic 26 or a second radiation characteristic 28, wherein the first radiation characteristic 26 and the second radiation characteristic 28 are different from each other. Figure 2A The electromagnetic radiation source 22 in the illustrated state (first switch configuration 34) emits electromagnetic radiation 24 having a first radiation characteristic 26, while Figure 2B The same electromagnetic radiation source 22 in the illustrated state (second switch configuration 36) emits electromagnetic radiation 24 having a second radiation characteristic 26. Where two or more such sources 22 are provided, all of these sources 22 may collectively emit with the same (first or second) radiation characteristic. In other variations, only a proper subset of one or more such sources 22 collectively emit with the same (first or second) radiation characteristic, while another proper subset of such sources 22 emits a radiation characteristic that, in some variations, is different from both the first radiation characteristic and the second radiation characteristic.

[0076] Tracker 16 also includes circuit 38 (at Figure 2A and Figure 2B ), the circuit being configured to selectively control the electromagnetic radiation source 22 to emit electromagnetic radiation 24 having a first radiation characteristic 26 in a first switching configuration 34, and to emit electromagnetic radiation 24 having a second radiation characteristic 26 in a second switching configuration 36.

[0077] Figure 2A and Figure 2B The first switch 32 shown is an exemplary mechanically operable switch in the form of a slide switch that maintains the switch configuration after being operated. Thus, the first switch 32 does not autonomously change from the first switch configuration 34 to the second switch configuration 36 (or vice versa). After moving the first switch 32 to the selected switch configuration, the user can operate the tracker 16 indefinitely in the selected switch configuration.

[0078] The first switch 32 may be spring biased against the operating direction. As an example, the first switch 32 may alternatively be a button. Such a button does not require lateral sliding movement and requires less space on the surface of the tracker 16. In such an embodiment, the first switch configuration 34 and the second switch configuration 36 may be provided in two different variations as described below.

[0079] In a first variation, the button alternates between a first switch configuration 34 and a second switch configuration 36 when operated, but remains in one switch configuration after operation (commonly referred to as a latching switch). This type of switch remains in one switch configuration indefinitely.

[0080] In a second variation, the button is biased toward one switch configuration (e.g., the first switch configuration) and switches to another switch configuration (e.g., the second switch configuration) only for the duration that the user operates the first switch 32 (commonly referred to as a "momentary switch"). Thus, the user can perform an input similar to a mouse click, which requires only minimal physical interaction with the switch 32.

[0081] In a third variation, the button is biased toward one switch configuration (e.g., the first switch configuration) and switches to another switch configuration (e.g., the second switch configuration) only within a fixed duration after the switch 32 is operated. The fixed duration can be shorter than manual input (e.g., shorter than 0.1s, 10ms, or 1ms), which can reduce power consumption, or can be longer (e.g., longer than 0.1s, 1s, or 10s) to ensure detection of the emitted electromagnetic radiation. The fixed duration can improve input efficiency. In addition, the operation of the switch 32 can be identified by the fixed duration (in addition to the emitted first radiation characteristic or the second radiation characteristic), which increases input accuracy.

[0082] Figure 4A-4C Another variation of the first switch 32 is shown, which includes a plurality of switch parts at two tracker components 16A and 16B1 or 16B2 that are removable from each other. Figure 4A-4C The first switch 32 comprises a first switch portion 70 , wherein the first switch portion 70 comprises a first electrode 72A, a second electrode 72B and a third electrode 72C as part of the circuit 38 , which are arranged at the first tracker component 16A which also carries the electromagnetic radiation source 22 .

[0083] The first switch 32 also includes two different second tracker components 16B1 and 16B2, which respectively carry a second switch portion 74 configured for electrically coupling to the first switch portion 70 of the first tracker component 16A and a third switch portion 76 configured for electrically coupling to the first switch portion 70. The second switch portion 74 includes a first electrical connector 78A, and the third switch portion 76 includes a second electrical connector 78B. Figure 4BThe second switch portion 74 is shown when electrically coupled to the first switch portion 70. Since the tracker components 16A and 16B1 or 16B2 are removable from each other and carry the first switch portion 70, the second switch portion 74, and the third switch portion 76, respectively, the first switch portion 70, the second switch portion 74, and the third switch portion 76 are also removable from each other.

[0084] The two different second tracker components 16B1 and 16B2 include coupling interfaces 80A and 80B, respectively, for coupling the tracker 16 to an object (not shown), such as a patient's bone or a surgical instrument. The first coupling interface 80A exemplarily includes a clamp that is configured to clamp on a patient's body part, such as a vertebra or tibia. The second coupling interface 80B exemplarily includes a ring with an offset screw that is configured to be coupled to a shaft of a surgical instrument. Of course, the coupling interfaces 80A, 80B can also be configured to be the same.

[0085] When the first tracker component 16A is mechanically coupled to the second tracker component 16B1, and therefore the first switch portion 70 is electrically coupled to the second switch portion 74, as shown in FIG. Figure 4B As shown, the first electrical connector 78A is arranged offset relative to the three electrodes 72A, 72B, and 72C, so that the first electrical connector 78A only electrically connects the first electrode 72A and the second electrode 72B, but not the third electrode 72C. Therefore, the first electrical connector 78A closes the circuit 38 (only in Figure 4A , Figure 4B ), which produces a first switching configuration 34 and thus emits electromagnetic radiation 24 having a first radiation characteristic 26.

[0086] When the first tracker component 16A is mechanically coupled to the second tracker component 16B2, and therefore the first switch portion 70 is electrically coupled to the third switch portion 76, as shown in FIG. Figure 4C As shown, the second electrical connector 78B is arranged offset relative to the three electrodes 72A, 72B, 72C, so that the second electrical connector 78B only electrically connects the second electrode 72B and the third electrode 72C, but not the first electrode 72A. Therefore, the second electrical connector 78B closes another part of the circuit 38 that is different from the part of the circuit 38 closed by the first electrical connector 78A, which produces the second switch configuration 36 and thus emits electromagnetic radiation 24 having the second radiation characteristic 28.

[0087] Thus, prior to a surgical procedure, a user may selectively couple the first switch portion 70 (i.e., the first tracker component 16A) to any of the second switch portion 74 and the third switch portion 76 (i.e., the second tracker component 16B1 or the alternative second tracker component 16B2), which causes the tracker 16 to emit electromagnetic radiation having the first radiation characteristic 26 or the second radiation characteristic 28 as described above. The surgical navigation system 10 may access an association between a corresponding object (which is associated with the first coupling interface 80A and the second coupling interface 80B) and the corresponding first radiation characteristic 26 and second radiation characteristic 28. Thus, based on the detected radiation characteristics 26, 28, the surgical navigation system 10 may distinguish between an object tracked when the first tracker component 16A is mechanically coupled to the second tracker component 16B1 and an object tracked when the first tracker component 16A is mechanically coupled to the second tracker component 16B1. In the case where two first tracker components 16A are provided, different objects may be tracked simultaneously by the navigation system 10 having a priori knowledge of the tracked objects.

[0088] The two different second tracker components 16B1 and 16B2 and Figure 4B , Figure 4C The first switch portion 70 and the second switch portion 74 shown in the figure are two separate entities. Alternatively, the second switch portion 74 and the third switch portion 76 are undertaken by a single switch portion provided at a single second tracker component (not shown), wherein the single switch portion "activates" the second switch portion 74 when coupled to the first switch portion 70 of the first tracker component 16A, for example, at a first relative angle (e.g., 0°), and the single switch portion "activates" the third switch portion 76 when coupled to the first switch portion 70 of the first tracker component 16A, for example, at a second relative angle (e.g., 180°) different from the first relative angle. The difference between the first relative angle and the second relative angle can be any angle greater than zero, such as 30°, 45°, 90°, 120°, and 180°.

[0089] Above Figure 4A-4C Variations of the first switch described in the context of include multiple electrodes selectively connected according to the position of the electrical connector. Alternatively, the first switch portion 70 may include only two electrodes that are configured to be electrically coupled to the second switch portion 74 and the third switch portion 76, wherein the second switch portion 74 and the third switch portion 76 differ in electrical characteristics (e.g., resistance, capacitance, or inductance). For example, the second switch portion 74 may be configured to electrically connect the two electrodes of the first switch portion 70 to a first resistor assigned to the first switch configuration 34, and the second switch portion 74 may be configured to electrically connect the two electrodes to a second resistor assigned to the second switch configuration 36 and different from the first resistor.

[0090] Alternatively, the second switch section 74 and the third switch section 76 may also include a portion of the circuit 38 that is configured to control one or more electromagnetic radiation sources 22 to emit electromagnetic radiation 24 including the first radiation characteristic 26 or the second radiation characteristic 28. For example, when the second switch section 74 is electrically coupled to the first switch section 70, the circuits of the first switch section 70 and the second switch section 74 together form a combined circuit that is configured to control the one or more electromagnetic radiation sources 22 to emit electromagnetic radiation 24 including the first radiation characteristic 26. On the other hand, when the third switch section 76 is electrically coupled to the first switch section 70, the circuits of the first switch section 70 and the third switch section 76 together form a combined circuit that is configured to control the one or more electromagnetic radiation sources 22 to emit electromagnetic radiation 24 including the second radiation characteristic 28.

[0091] Figure 5 A flow chart 100 of an embodiment of a method for operating tracker 16 is shown.

[0092] The method may optionally include providing power to one or more electromagnetic radiation sources 22 by a power source 30 in step 102. The method 100 also includes selectively emitting electromagnetic radiation 24 having a first radiation characteristic 26 in a first switch configuration 34 and emitting electromagnetic radiation 24 having a second radiation characteristic 28 in a second switch configuration 36 by the one or more sources 22 in step 104. To switch between the first radiation characteristic 26 and the second radiation characteristic 28, the switch 32 switches between the first switch configuration 34 and the second switch configuration 26, for example, as described above.

[0093] In some variations of the method, the tracker 16 allows the user to Figure 1As described above, the optical sensor 14 is configured to detect electromagnetic radiation emitted by the tracker 16. Based on the detected electromagnetic radiation, the processor 12 (or any other computer system in communication with the surgical navigation system 10) is configured to selectively identify (e.g., distinguish) a first switch configuration 34 or a second switch configuration 36 based on the radiation characteristics detected by the optical sensor 14. The processor 14 can access information about the first and second radiation characteristics (e.g., the operating frequency, wavelength, or geometric arrangement of the source 22, as will be further described below) that allows the switch configurations 34, 36 to be identified from the actual detected radiation characteristics. This information can be provided to the processor 12 during manufacturing, maintenance, or calibration. The information can be provided in the form of one or more predetermined radiation characteristics. In this way, the processor 12 can be configured to identify the first switch configuration 34 or the second switch configuration 36 by comparing the detected radiation characteristics with one or more predetermined radiation characteristics.

[0094] In particular, the processor 12 may be configured to assign a first tracking mode to the first switch configuration 34 and a second tracking mode to the second switch configuration 36. The first and second tracking modes may be associated with different surgical objects (e.g., a patient's body part, and an instrument) to which the tracker 16 is coupled. For example, the first tracking mode may be associated with tracking a patient, while the second tracking mode may be associated with tracking an instrument.

[0095] Alternatively, the first and second tracking modes may be associated with different body parts of the patient. For example, the first tracking mode may be associated with the patient's tibia, and the second mode may be associated with the patient's femur. In this case, the user may couple the tracker 16 to the tibia and operate the first switch 32 of the first tracker 16 to switch to the first switch configuration 34. In some embodiments, the user may additionally connect the second tracker 16 to the patient's femur and operate the first switch 32 of the second tracker 16 to switch to the second switch configuration 36. The processor 12 may identify the tracking mode of the corresponding tracker 16 based on the corresponding radiation characteristics. The processor 12 may determine that the first tracker 16 is coupled to the tibia (and, if present, may determine that the second tracker 16 is coupled to the femur) based on the identified tracking mode.

[0096] Where multiple electromagnetic radiation sources 22 are provided at a given tracker 16, the processor 12 may determine the position and / or orientation of the tracker 16 and, based thereon, the position and / or orientation of the surgical object to be tracked by the tracker 16. As an example, the processor 12 may process (e.g., calibrate or visualize) image data of the tibia and / or femur based on the detected position and / or orientation of each tracker 16. By setting the switch configuration of the first and second trackers 16, the user is able to effectively communicate with the processor 12 without having to use a mechanically operated input device of the computer system 18, such as a keyboard or mouse.

[0097] The user's ability to communicate with the surgical navigation system 10 is not limited to selecting a specific switch configuration (e.g., preoperatively). The user can communicate with the surgical navigation system 10 by switching the switch configuration (e.g., during a surgical procedure). To this end, the processor 12 can be configured to specifically identify the switch between the first switch configuration 34 and the second switch configuration 36. The processor 12 can, for example, identify the switch between the first switch configuration 34 and the second switch configuration 36 as a command issued by the user. The command can be related to surgical navigation. For example, the user can switch between the first switch configuration 34 and the second switch configuration 36 to instruct the surgical navigation system 10 to perform a certain processing step (e.g., change the visual presentation on the display). The instruction can optionally be related to other aspects of the surgical operation, such as the operation of a surgical instrument (the tracker 16 may or may not be connected to the instrument). In order to issue a command, the first switch 32 can be a button that is biased toward one switch configuration and switches to another switch configuration only during the duration of the user operating the first switch 32. For example, the surgical navigation system 10 can activate the suction tube during the duration of the surgeon operating the first switch 12.

[0098] It should be noted that the tracker 16 is not limited to providing only two switch configurations. The tracker 16 may have a first switch 32 with three, four, five, six or more switch configurations. Figure 6A-6C A variation of the first switch 32 having three switch configurations is shown, wherein the first switch configuration (in Figure 6A-6C ) is assigned to the first radiation characteristic 34, and the second switch configuration (in Figure 6A-6C The third switch configuration (in the middle position of the first switch 32) is assigned to the second radiation characteristic 28. Figure 6A-6CThe tracker 16 may be in the right position of the first switch 32 (in the middle) to allow the user to turn off the tracker 16. Alternatively, the tracker 16 may have a separate power switch for turning the tracker 16 on and off. The tracker 16 may be a disposable item, where the power switch may be operated exactly once to turn the tracker 16 on, in which case the switch may be turned on by removing a removable insulating material that interrupts a portion of the circuit 38.

[0099] Furthermore, the electromagnetic radiation source 22 is not limited to selectively adopting the first radiation characteristic 26 and the second radiation characteristic 28. Alternatively, the electromagnetic radiation source 22 may be configured to selectively emit electromagnetic radiation having more than two radiation characteristics 26, 28, such as three, four, five, six or more radiation characteristics. In this case, the first switch 32 may have a plurality of switch configurations, wherein each switch configuration is assigned to one of the plurality of radiation characteristics. Figure 6D-6F An embodiment of a tracker 16 is shown in which the electromagnetic radiation source 22 may be configured to selectively emit electromagnetic radiation having three different radiation characteristics, and the first switch 32 has three switch configurations, one switch configuration for each of the three radiation characteristics (and optionally a fourth switch configuration for turning the tracker 16 on or off).

[0100] As will be further described below, the change between the first radiation characteristic 24 and the second radiation characteristic 26 may not be visible to the user. However, the first radiation characteristic 24 and the second radiation characteristic 26 are linked to the first switch configuration 34 and the second switch configuration 36. To allow the user to more easily distinguish between the first radiation characteristic 24 and the second radiation characteristic 26, the tracker 16 may include an indicator configured to provide a first indication to the user under the first switch configuration 34 and a second indication to the user under the second switch configuration 36, wherein the first and second indications are at least one of optically and tactilely distinguishable to the user. The user can then identify the first radiation characteristic 24 and the second radiation characteristic 26 by identifying the associated first switch configuration 34 and the second switch configuration 36.

[0101] to this end, Fig. 7A and Figure 7B Shows something like Figure 2A and Figure 2B , but with a tracker 16 having a plurality of indicators 48A, 48B, 48C, 48D, the indicators are configured to provide a first indication in a first switch configuration 34 and a second indication in a second switch configuration 36. Specifically, Fig. 7A The tracker 16 is shown using a first switch configuration 34, Figure 7B Tracker 16 is shown employing a second switching configuration 36 . Fig. 7A and Figure 7B Combinations of indicators 48 are shown for simplicity in describing the indicators 48. However, it should be understood that the tracker 16 may have only one indicator 48 or any combination of indicators 48 described herein.

[0102] Fig. 7A and Figure 7B The illustrated tracker 16 includes an indicator light source 48A configured to emit visible light perceptible to the human eye. The indicator light source 48A is configured to emit light having a first visible wavelength (e.g., green light) under the first switch configuration 34 and to emit light having a second visible wavelength (e.g., red light) under the second switch configuration 36. Alternatively, the indicator light source 48A may be configured to emit light having a visible wavelength under one of the first switch configuration 34 and the second switch configuration 36 and not to emit light under the other of the first switch configuration 34 and the second switch configuration 36. Alternatively or additionally, the indicator light source 48A may be configured to operate at a third operating frequency perceptible to the human eye (e.g., 2 Hz) under the first switch configuration and to operate at a fourth operating frequency perceptible to the human eye (e.g., 6 Hz) under the second switch configuration.

[0103] Fig. 7A and Figure 7B The illustrated tracker 16 includes, as an additional or alternative indicator 48 , a first switch position indicator 48B configured to assign the first position of the first switch 32 to the first switch configuration 34 and to assign the second position of the first switch 32 to the second switch configuration 36 . Fig. 7A and Figure 7B The illustrated first switch position indicator 48B includes a number in the form of Roman numerals. Alternatively, the first switch position indicator 48B may include different symbols and / or terms (e.g., describing different tracking modes). For example, the first switch position indicator 48B may include terms indicating whether the tracker 16 is coupled to an instrument or a patient (e.g., the terms "instrument" and "patient," or "I" and "P"). Further optionally, the first switch position indicator 48B may include terms indicating the anatomical part of the patient to which the tracker 16 is connected (e.g., the terms "tibia" and "femur," or "T" and "F"). The first switch position indicator 48B may be formed as a protrusion or depression relative to the surrounding area of ​​the tracker 16 so that it can be tactilely distinguished by the user.

[0104] Fig. 7A and Figure 7B The illustrated tracker 16 includes a second switch position indicator 48C as an additional or alternative indicator 48, the second switch position indicator being configured to display a first symbol in the first switch configuration 34 and a second symbol in the second switch configuration 36. Fig. 7A and Figure 7B In the example shown, the first symbol is a white square and the second symbol is a black square. Alternatively, the first and second symbols may be any other set of symbols that are optically distinguishable by the user. The first switch 32 covers the second symbol under the first switch configuration 34 and exposes the second symbol under the second switch configuration 36. Similarly, the first symbol is covered by the first switch 32 under the second switch configuration 36 and exposed under the first switch configuration. Thus, the first symbol is visible to the user under the first switch configuration 34, while the second symbol is visible to the user under the second switch configuration 36. Obviously, one of the two symbols may be omitted so that when exposed, only a single symbol provides discrete visual feedback to the user.

[0105] Fig. 7A and Figure 7B The illustrated tracker 16 includes a tactile switch feature 48D as an additional or alternative indicator 48. The tactile switch feature 48D enables the user to more easily operate the first switch 32 and allows the user to tactilely determine the switch configuration of the first switch 32 (e.g., with reference to another tactile feature that remains stationary).

[0106] Different embodiments of specific radiation characteristics are described below. The different radiation characteristics are not mutually exclusive and can therefore be combined in any combination.

[0107] In one example, first radiation characteristic 26 includes emitting electromagnetic radiation 24 at a first operating frequency, and second radiation characteristic 28 includes emitting electromagnetic radiation at a second operating frequency different from the first operating frequency. The first and second operating frequencies each indicate a rate of periodic intensity variation of electromagnetic radiation 24. The frequency and rate may be visually distinguishable (e.g., selected to fall within a range of 0.5 Hz to 20 Hz, or to correspond to continuous radiation emission).

[0108] Fig. 8A The variation of the intensity of the electromagnetic radiation 24 at the first operating frequency is shown in a time diagram. It can be seen that the intensity alternates periodically between a higher intensity and a lower intensity. The operating frequency can be defined by the duration between two time points when the intensity switches from a lower intensity to a higher intensity.

[0109] Fig. 8A The lower intensity shown in is greater than zero. Alternatively, the lower intensity may be zero (or substantially zero). Figure 8B The intensity variation of electromagnetic radiation 24 at a first operating frequency is shown in a time diagram, wherein the intensity alternates between zero and an intensity greater than zero. Electromagnetic radiation source 22 operating at such an operating frequency alternates between emitting light and not emitting light at the operating frequency.

[0110] Figure 8C The change in intensity of the electromagnetic radiation 24 from the first operating frequency 40 to the second operating frequency is shown in a time diagram. Figure 8C In the example shown, the first operating frequency 40 is less than the second operating frequency 42. Alternatively, the first operating frequency 40 may be higher than the second operating frequency 42.

[0111] The change in operating frequency can be caused by the user switching the switch configuration as described below. Initially, the switch 32 is set in the first switch configuration 34 (see, for example, Figure 2A ). The circuit 38 is configured to selectively control the (at least one) electromagnetic radiation source 22 to emit electromagnetic radiation 24 at the first operating frequency 40 in the first switch configuration 34. The user then operates the switch 32 to switch from the first switch configuration 34 to the second switch configuration 36 (see, for example, Figure 2B ). Thus, the circuit 38 is configured to selectively control the (at least one) electromagnetic radiation source 22 to emit electromagnetic radiation 24 having the second operating frequency 42.

[0112] Figure 8C A single change in the radiation characteristic is shown. This change may be signaled by permanently maintaining the switch 32 (such as the one explained above) in the second switch configuration 36. The user may then use the tracker 16 while the at least one electromagnetic radiation source 22 emits electromagnetic radiation 24 having the second radiation characteristic (i.e., the second operating frequency 42).

[0113] During the surgical procedure, the radiation characteristics may be changed multiple times, such as two, three, or four times. Fig.8D The time diagram shows a first change 44 in the intensity of electromagnetic radiation 24 from first operating frequency 40 to second operating frequency 42, followed by a second change 46 back to first operating frequency 40. In essence, radiation characteristic 24 initially includes first operating frequency 40 and temporarily switches to second operating frequency 42.

[0114] The change of the radiation characteristic 24 can be achieved by operating a switch 32 (such as Figure 2A Alternatively, the radiation characteristic 24 may be changed using a switch 32 that is temporarily switched to the second switch configuration only for the duration that the user operates the switch 32 (or for a fixed duration after the user operates the switch 32).

[0115] Figure 8C and Fig.8DThe second operating frequency 42 shown in FIG. 4 is an operating frequency that is greater than zero. Alternatively, the second operating frequency 42 (or the first operating frequency 40) may be zero (or conversely, infinite), which corresponds to continuous emission of electromagnetic radiation 24. During the continuous emission, the intensity of the electromagnetic radiation 24 may be equal to the greater intensity of the first operating frequency 40, such as Fig. 8E Alternatively, the intensity may be smaller to reduce power consumption.

[0116] References Figure 1 The optical sensor 14 discussed (e.g., the camera described above) can have a frame rate that is greater (e.g., two times or three times larger) than the larger of the first operating frequency 40 and the second operating frequency 42 of the tracker 16. The optical sensor 14 having such a frame rate has a better ability to correctly resolve the first operating frequency 40 and the second operating frequency 42, and thus increases the accuracy of the surgical navigation system 10.

[0117] As described above, one difference between the first radiation characteristic 26 and the second radiation characteristic 28 is the operating frequency. Additionally or alternatively, the first radiation characteristic 26 may include emission of electromagnetic radiation having a first wavelength, and the second radiation characteristic 28 may include emission of electromagnetic radiation having a second wavelength different from the first wavelength. The first wavelength and the second wavelength may be within the visible spectrum (e.g., red and green or white and blue). The user may then easily distinguish between the first radiation characteristic 26 and the second radiation characteristic 28 based on the color of the light emitted by the at least one electromagnetic radiation source 22. Alternatively, the first and second wavelengths may be outside the visible spectrum, such as in the infrared spectrum. Such a tracker 16 is less distracting to the user and less affected by ambient lighting.

[0118] Figure 2A The tracker 16 shown includes only a single electromagnetic radiation source 22. However, as described above, the tracker 16 is not limited to a single electromagnetic radiation source 22. Alternatively, the tracker 16 may include a plurality of electromagnetic radiation sources 22, such as two, three, four, five, six, or more electromagnetic radiation sources 22. The circuit 38 may be configured to selectively control the plurality of electromagnetic radiation sources 22 to uniformly emit electromagnetic radiation 24 having a first radiation characteristic 26 in a first switch configuration 34, and to emit electromagnetic radiation 24 having a second radiation characteristic 28 in a second switch configuration 36. For example, when the first switch 32 is switched from the first switch configuration 34 to the second switch configuration 36, all of the electromagnetic radiation sources 22 emit light at the second operating frequency 42 and / or the second wavelength.

[0119] Alternatively or additionally, the change between the first radiation characteristic 26 and the second radiation characteristic 28 of the plurality of electromagnetic radiation sources 22 may include at least one of the following: (i) at least one of the electromagnetic radiation sources 22 starts emitting electromagnetic radiation 24 and (ii) at least one of the electromagnetic radiation sources 22 stops emitting electromagnetic radiation 24.

[0120] Fig. 9A and Fig. 9B An embodiment of a tracker 16 having multiple (here three) electromagnetic radiation sources 22 is shown, which can be controlled individually or in groups to stop, continue or start emitting electromagnetic radiation 24. That is, the tracker 16 includes a first electromagnetic radiation source 22A, a second electromagnetic radiation source 22B, and a third electromagnetic radiation source 22C (and optionally, a fourth electromagnetic radiation source). Fig. 9A As shown, when the first switch 32 is in the first switch configuration 34, the circuit 38 is configured to selectively control the plurality of electromagnetic radiation sources 22 to emit electromagnetic radiation 24 having a first radiation characteristic 26, wherein the first radiation characteristic 26 includes a first electromagnetic radiation source 22A and a second electromagnetic radiation source 22B that emit electromagnetic radiation and a third electromagnetic radiation source 22C that does not emit electromagnetic radiation.

[0121] like Fig. 9B As shown, once the first switch 32 is switched from the first switch configuration 34 to the second switch configuration 36, the circuit 38 is configured to selectively control the plurality of electromagnetic radiation sources 22 to emit electromagnetic radiation 24 having a second radiation characteristic 26, wherein the first electromagnetic radiation source 22A stops emitting electromagnetic radiation, the second electromagnetic radiation source 22B continues to emit electromagnetic radiation, and the third electromagnetic radiation source 22C stops emitting electromagnetic radiation.

[0122] The second electromagnetic radiation source 22B is spaced further from the third electromagnetic radiation source 22C than from the first electromagnetic radiation source 22A. The two sources 22B, 22C emitting electromagnetic radiation with the second radiation characteristic 28 are arranged at a different orientation and distance relative to each other than the two sources 22A, 22B emitting electromagnetic radiation with the first radiation characteristic 26. Therefore, the second radiation characteristic 26 is geometrically different from the first radiation characteristic 24, and by operating the first switch 32, the user can effectively change the geometric pattern of the electromagnetic radiation sources 22 emitting electromagnetic radiation 24.

[0123] In some variations, a fourth or fifth electromagnetic radiation source 22 may be provided. The plurality of electromagnetic radiation sources 22 may then be controlled such that at least (e.g., exactly) three electromagnetic radiation sources 22 emit (e.g., are switched on simultaneously) with the same radiation characteristic 26, 28 in each switch configuration 34, 36.

[0124] Fig. 10A and Fig. 10B Another variation of the tracker 16 is shown that includes eight electromagnetic radiation sources 22. Fig. 10A In the first switch configuration 34 shown, the three electromagnetic radiation sources 22 emit electromagnetic radiation 24 (at Fig. 10A The five electromagnetic radiation sources 22 do not emit electromagnetic radiation 24 (in Fig. 10A The tracker 16 has a lower power consumption when in the first switch configuration 34.

[0125] exist Fig. 10B In the illustrated second switch configuration 36, all eight electromagnetic radiation sources 22 emit electromagnetic radiation 24. When the tracker 16 is in the second switch configuration 36, the position and / or orientation of the tracker 16 may be more accurately determined by the surgical navigation system 10.

[0126] The tracker 16 described above includes one switch 32. However, the tracker 16 is not limited to a single switch 32. Alternatively, the tracker 16 may include a plurality of switches.

[0127] FIG. 11A to FIG. 11D A variation of tracker 16 is shown having multiple electromagnetic radiation sources 22, a first switch 32, and a second switch 50. Tracker 16 has six electromagnetic radiation sources 22A-22F. First subset 52 includes first electromagnetic radiation source 22A and second electromagnetic radiation source 22B assigned to first switch 32. Second subset 54 includes third electromagnetic radiation source 22C and fourth electromagnetic radiation source 22D assigned to second switch 50.

[0128] The switch 32 is configured to be set by the user in a first switch configuration ( Fig.11A and Fig. 11C ) and the second switch configuration ( Fig. 11B and Fig.11D Another switch 50 is configured to be operated by the user in a third switch configuration ( Fig.11A and Fig. 11B ) and the fourth switch configuration ( Fig. 11C and Fig.11D ) between the two.

[0129] The first subset 52 of the plurality of electromagnetic radiation sources 22 is configured to selectively emit electromagnetic radiation 24 having a first partial radiation characteristic or a second partial radiation characteristic. The first partial radiation characteristic includes a first electromagnetic radiation source 22A that emits electromagnetic radiation and a second electromagnetic radiation source 22B that does not emit electromagnetic radiation, such as Fig.11A and Fig. 11C The second part of the radiation characteristics includes a first electromagnetic radiation source 22A that does not emit electromagnetic radiation and a second electromagnetic radiation source 22B that emits electromagnetic radiation, such as Fig. 11BEssentially, the difference in the radiation characteristics of the first and second portions is whether the first source 22A or the second source 22B emits electromagnetic radiation.

[0130] The second subset 54 of the plurality of electromagnetic radiation sources 22 is configured to selectively emit electromagnetic radiation 24 having a third partial radiation characteristic or a fourth partial radiation characteristic. The third partial radiation characteristic includes a third electromagnetic radiation source 22C that emits electromagnetic radiation and a fourth electromagnetic radiation source 22D that does not emit electromagnetic radiation, such as Fig.11A The fourth part of the radiation characteristics includes a third electromagnetic radiation source 22C that does not emit electromagnetic radiation and a fourth electromagnetic radiation source 22D that emits electromagnetic radiation, as shown in FIG. Fig. 11C Likewise, the third and fourth portion radiation characteristics differ in whether the third source 22C or the fourth source 22D emits electromagnetic radiation.

[0131] The two switches 32, 50 are configured to be operated by a user to change only the partial radiation characteristics of each assigned subset 52, 54 of the electromagnetic radiation sources 22A-22D. Thus, the user can operate the first switch 32 to change the partial radiation characteristics of the first subset 52 without changing the partial radiation characteristics of the second subset 52. Vice versa, the user can operate the second switch 50 to change the partial radiation characteristics of the second subset 54 without changing the partial radiation characteristics of the first subset 52.

[0132] The radiation characteristic 24 of the entire tracker 16 includes the partial radiation characteristics of each subset 52, 54. Since each subset 52, 54 can switch between two partial radiation characteristics, the tracker 16 has Figures 11A-11D The four radiation characteristics shown in . Fig.11A Tracker 16 is shown having a first radiation characteristic including a first partial radiation characteristic of a first subset 52 and a third partial radiation characteristic of a second subset 54 . Fig. 11B Tracker 16 is shown having a second radiation characteristic including a second partial radiation characteristic of first subset 52 and a third partial radiation characteristic of second subset 54 . Fig. 11C Tracker 16 is shown having a third radiation characteristic including a first partial radiation characteristic of first subset 52 and a fourth partial radiation characteristic of second subset 54 . Fig.11D Tracker 16 is shown having a fourth radiation characteristic including a second partial radiation characteristic of first subset 52 and a fourth partial radiation characteristic of second subset 54 .

[0133] In some variations, radiation sources 22E and 22F may be included in first subset 52 and second subset 54, respectively. In some variations, sources 22E and 22F may be omitted.

[0134] Figures 11A-11DThe tracker 16 shown includes two subsets of electromagnetic radiation sources 22. Alternatively, the tracker 16 may include more than two subsets of electromagnetic radiation sources 22. Fig. 12A The tracker 16 shown has four subsets 52, 54, 56, 58 of electromagnetic radiation sources 22 and four switches 32, 50, 60, 62. Each switch 32, 50, 60, 62 is assigned to one of the four subsets 52, 54, 56, 58 and allows switching between two partial radiation characteristics of each assigned subset 52, 54, 56, 58. The radiation characteristic 24 of the entire tracker 16 includes the partial radiation characteristics of each subset 52, 54, 60, 62 and thus includes sixteen different radiation characteristics.

[0135] Figures 11A-11D and Fig. 12A The subsets of trackers 16 shown all include exactly two electromagnetic radiation sources 22, wherein each subset can change between two different partial radiation characteristics. Alternatively, trackers 16 can include subsets having more than two (e.g., three, four, or more) electromagnetic radiation sources 22, and / or include subsets each having more than two (e.g., three, four, or more) different partial radiation characteristics. Fig. 12B A variation of the tracker 16 is shown having four subsets 52, 54, 56, 58, and four switches 32, 50, 60, 62, each subset having four electromagnetic radiation sources 22, each switch being assigned to one of the respective subsets 52, 54, 56, 58. Furthermore, each switch 32, 50, 60, 62 has four switch configurations that allow selection of one electromagnetic radiation source 22 in the assigned subset 52, 54, 56, 58 for emitting electromagnetic radiation.

[0136] For the above subsets, each partial radiation characteristic includes exactly one electromagnetic radiation source 22 that emits electromagnetic radiation, while the remaining electromagnetic radiation sources 22 of the subset do not emit electromagnetic radiation. Thus, changing the partial radiation characteristic substantially changes the single source 22 in the subset that emits electromagnetic radiation. However, the partial radiation characteristic may include more than just a single source 22 that emits electromagnetic radiation. The partial radiation characteristic may include multiple (e.g., three, four, or more) sources 22 in the associated subset that emit electromagnetic radiation. Thus, changing the partial radiation characteristic may include stopping or continuing to emit electromagnetic radiation for multiple sources 22 of the associated subset.

[0137] Note that the electromagnetic radiation sources 22 of the tracker 16 shown in Figures 10 and 11 are preferably arranged asymmetrically to prevent ambiguous orientation and / or position of the tracker 16 when tracking. In addition, the electromagnetic radiation sources 22 are preferably arranged in such a way that any geometric arrangement of the electromagnetic radiation sources 22 that may be the result of different switch configurations is also asymmetrical. The electromagnetic radiation sources 22 may also be arranged in such a way that any geometric arrangement of the electromagnetic radiation sources 22 that may be the result of different switch configurations is unique.

[0138] The features described with respect to the exemplary embodiments shown in the accompanying drawings can be easily combined to produce different embodiments. Therefore, it is obvious that the present disclosure can be changed in many ways. These changes should not be considered as departing from the scope of the present invention defined by the appended claims.

Claims

1. A tracker for a surgical navigation system, the tracker comprising: a first switch configured to be operated between a first switch configuration and a second switch configuration; one or more electromagnetic radiation sources configured to selectively emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic; as well as circuitry configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having the first radiation characteristic in the first switch configuration and to emit electromagnetic radiation having the second radiation characteristic in the second switch configuration, wherein the second radiation characteristic is different from the first radiation characteristic, and The first switch is preconfigured to adopt the first switch configuration and is suitable for switching from the first switch configuration to the second switch configuration only during a duration when the first switch is operated or within a fixed duration after the first switch is operated.

2. The tracker according to claim 1, wherein: The first radiation characteristic comprises emitting electromagnetic radiation at a first operating frequency, and the second radiation characteristic comprises emitting electromagnetic radiation at a second operating frequency different from the first operating frequency, wherein each of the first operating frequency and the second operating frequency indicates a rate of periodic intensity change of the electromagnetic radiation.

3. The tracker according to claim 2, wherein: One of the first operating frequency and the second operating frequency is zero, wherein electromagnetic radiation is continuously emitted.

4. The tracker according to claim 1, wherein: The first radiation characteristic comprises emitting electromagnetic radiation having a first wavelength, and the second radiation characteristic comprises emitting electromagnetic radiation having a second wavelength different from the first wavelength.

5. The tracker according to claim 1, wherein: The tracker includes a plurality of electromagnetic radiation sources; and wherein The changing between the first radiation characteristic and the second radiation characteristic of the plurality of electromagnetic radiation sources comprises at least one of: - at least one electromagnetic radiation source starts emitting electromagnetic radiation; as well as - At least one electromagnetic radiation source ceases to emit electromagnetic radiation.

6. The tracker according to claim 5, wherein: The first subset of electromagnetic radiation sources includes only two electromagnetic radiation sources; as well as Therein, in the first radiation characteristic, only one source of the first subset is configured to emit electromagnetic radiation, and in the second radiation characteristic, only another source of the first subset is configured to emit electromagnetic radiation.

7. The tracker according to claim 5, comprising a second switch configured to be operated between a third switch configuration and a fourth switch configuration; in, A first subset of the plurality of electromagnetic radiation sources is assigned to the first switch and a second subset of the plurality of electromagnetic radiation sources is assigned to the second switch; wherein the first subset of the plurality of electromagnetic radiation sources is configured to selectively emit electromagnetic radiation having a first partial radiation characteristic or a second partial radiation characteristic, and wherein the second subset of the plurality of electromagnetic radiation sources is configured to selectively emit electromagnetic radiation having a third partial radiation characteristic or a fourth partial radiation characteristic; and Wherein, the first switch and the second switch are configured to be operated to change only part of the radiation characteristics of a subset of each assigned electromagnetic radiation source.

8. The tracker according to claim 1, wherein: The tracker includes an indicator configured to provide a first indication in the first switch configuration and to provide a second indication in the second switch configuration, wherein the first indication and the second indication are at least one of optically distinguishable and tactilely distinguishable to a user.

9. The tracker according to claim 1, comprising: One of a power source and a wireless power receiving device.

10. A tracker according to any one of the preceding claims, comprising One or more passive tracking elements configured to reflect electromagnetic radiation.

11. The tracker according to claim 1, wherein: The first switch has more than two switch configurations; The one or more electromagnetic radiation sources are configured to selectively emit electromagnetic radiation having a number of radiation characteristics at least equal to the number of switch configurations, wherein each switch configuration is assigned to one of the radiation characteristics.

12. The tracker according to claim 1, wherein: The first switch comprises a mechanical switch configured to be operated by a user.

13. The tracker according to claim 1, wherein: The first switch comprises: A first switch part; a second switch portion configured to be electrically coupled to the first switch portion; and a third switch portion configured to be electrically coupled to the first switch portion; Wherein, when the second switch portion is electrically coupled to the first switch portion, the first switch is in the first switch configuration, and when the third switch portion is electrically coupled to the first switch portion, the first switch is in the second switch configuration.

14. The tracker according to claim 13, wherein: The tracker includes a first tracker component and at least one second tracker component, wherein the at least one second tracker component is one of movable relative to the first tracker component and removable from the first tracker component, wherein the first switch part is provided at the first tracker component, and the second switch part and the third switch part are provided at the at least one second tracker component jointly or individually.

15. The tracker according to claim 14, wherein: one of the first tracker component and the at least one second tracker component carries the one or more electromagnetic radiation sources; as well as The other of the first tracker component and the at least one second tracker component comprises an interface for coupling the tracker to an object to be tracked.

16. A surgical navigation system, comprising A tracker, the tracker comprising a first switch, the first switch being configured to be operated between a first switch configuration and a second switch configuration, the tracker further comprising a circuit and one or more electromagnetic radiation sources, the one or more electromagnetic radiation sources being configured to selectively emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic, the circuit being configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having the first radiation characteristic in the first switch configuration and to emit electromagnetic radiation having the second radiation characteristic in the second switch configuration, wherein the second radiation characteristic is different from the first radiation characteristic, and wherein the first switch is preconfigured to adopt the first switch configuration and is adapted to switch from the first switch configuration to the second switch configuration only for a duration while the first switch is operated or for a fixed duration after the first switch is operated; an optical sensor capable of detecting different radiation characteristics of the tracker; and A processor is configured to selectively identify the first switch configuration or the second switch configuration based on a characteristic of radiation detected by the optical sensor.

17. The surgical navigation system according to claim 16, wherein: The processor is configured to assign a first tracking mode to the first switch configuration and to assign a second tracking mode to the second switch configuration.

18. The surgical navigation system according to claim 16, wherein: The first radiation characteristic comprises emitting electromagnetic radiation at a first operating frequency, and the second radiation characteristic comprises emitting electromagnetic radiation at a second operating frequency different from the first operating frequency, wherein each of the first operating frequency and the second operating frequency indicates a rate of periodic intensity change of the electromagnetic radiation. Wherein the optical sensor is a camera having a frame rate that is at least twice the larger of the first operating frequency and the second operating frequency of the tracker.

19. A method for operating a tracker for a surgical navigation system, the tracker comprising a first switch, one or more electromagnetic radiation sources, and a circuit, the first switch being configured to be operated between a first switch configuration and a second switch configuration, the first switch being preconfigured to adopt the first switch configuration and being suitable for switching from the first switch configuration to the second switch configuration only during the duration of the operation of the first switch or within a fixed duration after the operation of the first switch, the circuit being configured to selectively control the one or more electromagnetic radiation sources to emit electromagnetic radiation having a first radiation characteristic or a second radiation characteristic, wherein The second radiation characteristic is different from the first radiation characteristic, wherein the method comprises emitting, by the one or more electromagnetic radiation sources in the first switching configuration, electromagnetic radiation having the first radiation characteristic; operating the first switch to switch from the first switch configuration to the second switch configuration; and Electromagnetic radiation having the second radiation characteristic is emitted by the one or more electromagnetic radiation sources in the second switching configuration.

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