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1. WO2007141784 - CONTROLLED STEERING OF A FLEXIBLE NEEDLE

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS

1. A system for the insertion of a needle having a tip into a tissue, according to a predetermined trajectory, comprising:
a robot for maneuvering said needle into said tissue;
an imaging system for ascertaining the trajectory of said needle in real time; and
a control system controlling said robot motion according to differences between said ascertained trajectory and said predetermined trajectory,
wherein said controller utilizes a model of said needle as a flexible beam having a plurality of virtual springs connected laterally thereto to simulate lateral forces exerted by said tissue on said needle, and whose trajectory through said tissue is determined by the influence of said plurality of virtual springs on said needle.

2. A system according to claim 1 wherein said system determines the needle trajectory taking into account the effect of motion of said tissue as a result of insertion of said needle.

3. A system according to claim 1 wherein said system determines the needle trajectory taking into account the change in the stiffness coefficients of at least some of said virtual springs as a result of the trajectory of said needle.

4. A system according to any of the previous claims, wherein said predetermined trajectory of said needle comprises a target for said tip of said needle.

5. A system according to claim 4 wherein said predetermined trajectory further comprises at least one region where access is forbidden to said needle.

6. A system according to any of the previous claims, wherein said robot motion comprises at least some of inward, lateral and angular motion.

7. A system according to claim 6, wherein said robot motion comprises up to 6 degrees of freedom.

8. A system according to any of the previous claims wherein said imaging system is any one of an X-ray fluoroscopic system, a CT system, an MRI system, an ultrasonic system, a system using electromagnetic navigation, and a system using optical navigation.

9. A system according to any of the previous claims wherein said imaging system is aligned to provide images of a plane generally including the directions of said lateral and inward motion.

10. A system according to any of the previous claims wherein said control system determines the deviation of the real time position of said tip determined by image processing of an image obtained from said imaging system, from the planned position of said tip according to said predetermined trajectory, and calculates the motion to be applied to said robot to reduce said deviation by use of said virtual springs model.

11. A system according to any of the previous claims wherein said control system utilizes an inverse kinematics solution applied to said virtual springs model to calculate the required motion to be imparted to said needle to follow said planned trajectory.

12. A system according to any of the previous claims wherein said control system uses the shape of the needle as detected from the images, to determine in real time changes in the stiffness properties of the tissue which the needle is traversing.

13. A system according to claim 12 and wherein said control system uses these changed tissue properties to adjust the needle path in real time in accordance with the tissue being negotiated.

14. A system according to claim 12, further comprising a force sensor to determine the forces exerted on said needle at its base, and wherein said control system also uses said forces to determine in real time changes in the stiffness properties of the tissue which the needle is traversing.

15. A system according to any of the previous claims, wherein said predetermined trajectory is divided into increments, and the control system performs the insertion according to these increments, and in accordance with the real time results obtained at least from the imaging system at each incremental insertion point.

16. A system according to any of the previous claims, wherein said needle comprises at least one position sensor, such that said needle can be detected using said at least one position sensor.

17. A system according to claim 17, wherein said at least one position sensor is an electromagnetic position sensor.

18. A system according to either of claims 16 and 17, further comprising a registration system such that the co-ordinate system of said robot, to which said needle is attached, can be related to the co-ordinate system of the imaging system in which the tissue features are determined.

19. A system for controlling the insertion of a needle into a deformable tissue, according to a predetermined trajectory, comprising:
a robot for maneuvering said needle into said tissue;
an imaging system for ascertaining the trajectory of said needle in real time; and
a control system controlling said robot motion according to differences between said ascertained trajectory and said predetermined trajectory;
wherein said control system:
(i) uses the trajectory of the imaged needle to determine changes in the elastic properties of the tissue through which the needle is passing;
ii) utilizes these tissue properties to adjust, according to the tissue being negotiated, an elastic model of the tissue along the path of the needle;
(iii) obtains an inverse kinematic solution for the motion of said needle though said tissue; and
(iv) instructs said robot to maneuver said needle into said tissue according to said solution.

20. A system according to claim 19, and further comprising a force sensor to determine the forces exerted on said needle at its base, and wherein said control system performs the additional step of also using said forces to determine changes in the elastic properties of the tissue which the needle is traversing.

21. A system according to claim 19, and wherein said predetermined trajectory is divided into increments, and said control system performs said insertion incrementally according to the real time results obtained from said imaging system.

22. A method of controlling the insertion of a needle into a tissue, comprising the steps of:
determining a preplanned trajectory to be followed by said needle;
mounting the base of said needle on a robot for maneuvering said needle into said tissue;
generating images of said tissue to show the trajectory of said needle in real time;
controlling the motion of said robot according to differences between said realtime trajectory and said preplanned trajectory; and
utilizing a model of said needle as a flexible beam having a plurality of virtual springs connected laterally thereto to simulate lateral forces exerted by said tissue on said needle, and calculating said trajectory through said tissue on the basis of the influence of said plurality of virtual springs on said needle.