System and method for estimating the spatial position of a tool within an object

Patent metadata

Field	Value
Publication number	US-10342622-B2
Application number	US-201715811674-A
Country	US
Kind code	B2
Filing date	Nov 13, 2017
Priority date	May 21, 2012
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

The invention relates to a system for estimating the spatial position (pose) of a tool (2) within an object (1), particularly in the form of a human bone that is to be machined with said tool, comprising: a sensor (21) being designed to be coupled to said tool (2), which sensor (21) is further designed to generate an sensor output signal (31) upon machining of said object (1) along an actual trajectory (30), which sensor output signal (31) depends on a material property of said object along said actual trajectory (30), an analyzing means being designed to determine a correlation between said sensor output signal (31) upon machining said object (1) and a plurality of pre-determined candidate output signals (42), each candidate output signal (42) being generated in beforehand using said material property along an associated model trajectory (40) in a model of said object (1), and wherein said analyzing means is designed to estimate a spatial position of the tool (2) within the object (1) using the model trajectory (40) whose associated candidate output signal (42) has the highest correlation with the sensor output signal (31), for instance. The invention further relates to a method for estimating the pose of the tool (2), as well as a computer program product.

First claim

The invention claimed is:

1. A system for estimating the spatial position of a surgical tool within bone during surgery, comprising:
a sensor coupled to the surgical tool, wherein the sensor generates a sensor output signal upon machining of a bone with the tool along an actual trajectory, wherein the sensor output signal depends on the density of the bone along the actual trajectory,
an analysing means for determining a spatial position of the surgical tool within the bone, wherein for determining the spatial position the analyzing means determines a correlation between the sensor output signal and at least one pre-determined candidate output signal, wherein the pre-determined candidate output signal is generated beforehand using the known density of the bone along an associated model trajectory in a model of the bone.

2. The system of claim 1 , wherein the analysing means determines a correlation between the sensor output signal and a plurality of pre-determined candidate output signals, wherein each pre-determined candidate output signal is generated beforehand using the known density of the bone along an associated model trajectory in a model of the bone.

3. The system of claim 2 , wherein the analysing means determines the pre-determined candidate output signal that correlates best with the sensor output signal and accordingly determines the spatial position of the surgical tool within the bone as an end point of the model trajectory associated to the best-correlated candidate output signal.

4. The system of claim 1 , wherein the surgical tool is a surgical drill.

5. The system of claim 4 , wherein the system further comprises a robotic arm coupled to the surgical tool.

6. The system of claim 1 , wherein the bone is a mastoid bone.

7. The system of claim 1 , wherein the bone is selected from the group consisting of skull, vertebra and long bone.

8. The system of claim 2 , wherein at least one of the pre-determined candidate output signal, the model trajectory and the model of the bone are determined using a tomographic image.

9. The system of claim 2 , wherein the analysing means computes a weight associated with the model trajectory of each pre-determined candidate output signal, wherein the weight is a function of the difference between the sensor output signal and the pre-determined candidate output signal and the spatial position of the surgical tool in the bone is estimated by a corresponding weighted average of the model trajectories.

10. A method for estimating the spatial position of a surgical tool within bone during surgery, comprising:
generating a sensor output signal upon machining of a bone with the tool along an actual trajectory, wherein the sensor output signal depends on the density of the bone along the actual trajectory,
providing at least one pre-determined candidate output signal, wherein the pre-determined candidate output signal is generated beforehand using the known density of the bone along an associated model trajectory in a model of the bone, and
determining a correlation between the sensor output signal and the at least one pre-determined candidate output signal using an analysing means.

11. The method of claim 10 , wherein the analysing means determines a correlation between the sensor output signal and a plurality of pre-determined candidate output signals, wherein each pre-determined candidate output signal is generated beforehand using the known density of the bone along an associated model trajectory in a model of the bone.

12. The method of claim 11 , wherein the analysing means determines the pre-determined candidate output signal that correlates best with the sensor output signal and accordingly determines the spatial position of the surgical tool within the bone as an end point of the model trajectory associated to the best-correlated candidate output signal.

13. The method of claim 10 , wherein the surgical tool is a surgical drill.

14. The method of claim 13 , wherein the machining of the bone is accomplished through the coupling of the surgical drill with a robotic arm.

15. The method of claim 13 , wherein the machining of the bone is accomplished by manual operation of the surgical drill.

16. The method of claim 10 , wherein the bone is a mastoid bone.

17. The method of claim 10 , wherein the bone is selected from the group consisting of skull, vertebra and long bone.

18. The method of claim 11 , further comprising the step of generating at least one of the pre-determined candidate output signal, the model trajectory and the model of the bone using a tomographic image.

19. The method of claim 11 , further comprising the step of the analysing means computing a weight associated with the model trajectory of each pre-determined candidate output signal, wherein the weight is a function of the difference between the sensor output signal and the pre-determined candidate output signal and the spatial position of the surgical tool in the bone is estimated by a corresponding weighted average of the model trajectories.

Assignees

• Univ Bern

Inventors

• Bell Brett J
• Weber Stefan
• Williamson Tom

Classifications

• G06T7/74

  involving reference images or patches · CPC title

• A61B34/30 Primary

  Surgical robots · CPC title

• G06T2207/10072

  Tomographic images · CPC title

• G06T2207/30241

  Trajectory · CPC title

• A61B2090/065

  for measuring contact or contact pressure · CPC title