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EP-4740891-A2 - TRACKER FOR A SURGICAL NAVIGATION SYSTEM

EP4740891A2EP 4740891 A2EP4740891 A2EP 4740891A2EP-4740891-A2

Abstract

A tracker for a surgical navigation system and a surgical navigation system are provided. The tracker comprises a carrier and an electrical circuit disposed on the carrier. The electrical circuit comprises an arrangement of more than two infrared light emitting diodes, IR-LEDs, wherein the arrangement has no rotational symmetry, and a wireless power reception device configured to receive power wirelessly, wherein the wireless power reception device is configured to provide power to operate at least one IR-LED of the arrangement. The electrical circuit is configured to limit a current for at least one of the at least one IR-LED to not exceed 15mA.

Inventors

  • GHANAM, Fadi
  • Breisacher, Jochen
  • HERRMANN, FLORIAN
  • UMBDENSTOCK, Emeric
  • ZIMMERMANN, REINHOLD
  • GAMM, GERD ULRICH

Assignees

  • Stryker European Operations Holdings LLC

Dates

Publication Date
20260513
Application Date
20180419

Claims (15)

  1. A tracker (10) for a surgical navigation system, the tracker (10) comprising a carrier (12); and an electrical circuit (40) disposed on the carrier (12), wherein the electrical circuit (40) comprises: at least one infrared light emitting diode, IR-LED, (14); and a wireless power reception device (17) configured to receive power wirelessly, wherein the wireless power reception device (17) is configured to provide power to operate the at least one IR-LED (14), wherein the electrical circuit (40) is configured to limit a current for at least one of the at least one IR-LED (14) to not exceed 15mA.
  2. The tracker (10) according to claim 1, wherein the tracker (10) is configured for continuous or quasi-continuous operation of at least one of the at least one IR-LED (14).
  3. The tracker (10) according to claim 1 or 2, wherein the electrical circuit (40) comprises at least one resistor (24) configured to limit the current for the at least one of the at least one IR-LED (14), wherein the current for the at least one of the at least one IR-LED (14) is limited by an internal electrical resistance of the at least one of the at least one IR-LED (14) and an electrical resistance of the at least one resistor (24) electrically connected in series to the at least one of the at least one IR-LED (14).
  4. The tracker (10) according to any of the preceding claims, wherein the wireless power reception device (17) is configured for receiving power through at least one near field technique selected from inductive coupling, capacitive coupling and magnetodynamic coupling.
  5. The tracker (10) according to any of the preceding claims, wherein the tracker (10) comprises an arrangement of more than two IR-LEDs (14) that has no mirror symmetry.
  6. The tracker (10) according to any of the preceding claims, wherein the electrical circuit (40) is configured to limit a radiant intensity of at least one of the at least one IR-LED (14) to not exceed 40µW/sr.
  7. The tracker (10) according to any of the preceding claims, wherein the tracker (10) comprises a plurality of IR-LEDs (14) and a distance between at least two of the plurality of IR-LEDs (14) is smaller than 40mm.
  8. The tracker (10) according to any of the preceding claims, further comprising an interface (26) that is configured for coupling the tracker (10) to a surgical instrument (34) or to a patient.
  9. The tracker (10) according to any of the preceding claims, wherein the tracker (10) comprises a plurality of IR-LEDs (14) and the tracker (10) is configured to operate at least two of the plurality of the IR-LEDs (14) simultaneously.
  10. The tracker (10) according to any of the preceding claims, wherein the weight of the tracker (10) does not exceed 35 g.
  11. The tracker (10) according to any of the preceding claims, wherein the electrical circuit comprises at least one switch (22) configured to electrically close at least one portion of the electrical circuit, wherein the tracker (10) is a disposable item and the switch is operable exactly once to close the at least one portion of the electrical circuit.
  12. A surgical navigation system (50) comprising a tracker (10) according to any of the preceding claims; and a camera (60) capable of detecting light of the at least one IR-LED (14) and of generating a camera signal indicative of the detected light.
  13. The surgical navigation system (50) according to claim 12, further comprising a processor (68) capable of receiving the camera signal and at least one of registering and tracking the tracker (10) based on the received sensor signal.
  14. The surgical navigation system (50) according to claim 12 or 13, wherein the camera (60) comprises at least one two-dimensional image sensor (66) and/or wherein the camera (60) comprises at least one lens (64) for focusing the infrared light emitted by the at least one IR-LED (14).
  15. A method (70) of operating a tracker (10), wherein the tracker (10) comprises a carrier (12) and an electrical circuit (40) disposed on the carrier (12), wherein the electrical circuit (40) comprises at least one infrared light emitting diode, IR-LED, (14), wherein the electrical circuit further comprises a wireless power reception device (17) configured to receive power wirelessly, the method (70) comprising providing (72), by the wireless power reception device (17), power to operate the at least one IR-LED (14); and limiting (74), by the electrical circuit (40), a current for at least one of the at least one IR-LED (14) to not exceed 15mA.

Description

Technical Field The present disclosure generally relates to a tracker for use in surgical navigation. In particular, a tracker comprising an infrared light emitting diode is presented. Background During surgery, a surgeon often uses instruments that have to be inserted into the body of a patient. Once inside the patient's body, the surgeon loses vision of the tip of the instrument. In order to help the surgeon navigate the instrument in such a case, a surgical navigation system can be used that tracks the instrument and provides visual or acoustic guidance to the surgeon. One way to track the instrument is to attach a tracker onto the instrument. A camera in the operating room detects the tracker and generates data that is used to calculate the position of the tracker and, therefore, of the instrument. Commonly, the patient is tracked also, which enables calculating the position of the instrument relative to the patient. Surgical navigation can be carried out using passive or active trackers. A passive tracker comprises markers that reflect light. The reflected light can be detected by the camera. However, passive markers are susceptible to contamination (e.g., with blood), which impairs their reflectivity and consequently the accuracy of the surgical navigation. An active tracker, on the other hand, generates light (e.g., via a light emitting diode) that can be detected by the camera. Therefore, a higher brightness can be achieved and light generation is not dependent on ambient lightning. However, light generation requires a power source for the tracker, usually in the form of a battery pack or a power cord. The weight of the battery pack or of the power cord greatly affects the centre of gravity of the instrument. This can make holding the instrument tiresome for the surgeon. Furthermore, structurally weak instruments like biopsy needles may deform or even be damaged by the weight of the tracker. The power consumption of the tracker may be reduced by operating the light emitting diodes in a pulsed manner. However, such a pulsed operation requires synchronization with the navigation camera, which leads to additional processing steps and increases the complexity of the tracker in view of the required communication interface. Summary There is a need for a tracker that solves one or more of the aforementioned problems. According to one aspect, a tracker for a surgical navigation system is provided. The tracker comprises a carrier and an electrical circuit disposed on the carrier. The electrical circuit comprises an arrangement of more than two infrared light emitting diodes, IR-LEDs, wherein the arrangement has no rotational symmetry. The electrical circuit further comprises a battery or a wireless power reception device configured to receive power wirelessly, wherein the battery or the wireless power reception device is configured to provide power to operate at least one IR-LED of the arrangement. The electrical circuit is configured to limit a current for at least one of the at least one IR-LED to not exceed 15mA. The tracker may comprise three, four or more IR-LEDs. The tracker may comprise an arrangement of the more than two IR-LEDs that has no mirror symmetry. The tracker may comprise an arrangement of the more than two IR-LEDs such that each distance between any two IR-LEDs is unique. The carrier may be manufactured from a light-weight non-metallic material, such as a polymer. The electrical circuit may comprise a printed circuit board. The electrical circuit may comprise at least one switch configured to electrically open and/or close at least a portion of the electrical circuit (e.g., to jointly switch the IR-LEDs on or off). The tracker may be a disposable item. In such a case, the switch may be operable exactly once to close the at least one portion of the electrical circuit. Such a switch may comprise an isolating material, such as paper and/or plastic. The isolating material may be physically removable from the tracker. Operation of the IR-LED may comprise illumination of the IR-LED. The electrical circuit may be configured to limit the current for at least one of the at least one IR-LED to not exceed 10mA, preferably 5mA, more preferably 3mA. The electrical circuit may be configured to limit the current for some or all of the IR-LEDs of the tracker to 15 mA or less as indicated above. The tracker may be configured for continuous operation of at least one of the at least one IR-LED. The tracker may be configured for continuous operation of some or all of the IR-LEDs. The tracker may be configured for quasi-continuous operation of at least one of the at least one IR-LED. The quasi-continuous operation may be performed at an operation frequency of over 0.5 kHz, over 1 kHz or over 4 kHz. Since a continuous or quasi-continuous operation requires no synchronization with a camera, no communication interface (such as a transceiver) for communication with the camera is necessary. The tracker may thus not