Medical Robotics: Current Research Trends

1. Medical Robotics:Current Research Trends

3. Introduction Potential benefits of medical robotics include: Coupling of information to action in the OR Increase in accuracy of task performance Operation in tightly constrained environments Tool support in between phases of operation Hyperspectral sensing (X-ray, IR, magnetic, etc) Tremor mitigation Remote surgery (meters to 1000�s kilometers) Navigational planning through tracking

4. Robots & Humans

5. Challenges (I) Manipulation Safety in shared workspace with humans Sterile environments High dexterity in small spaces Possible interference from outside sources (magnetic)

6. Challenges (II) Registration Determination of geometric transformation matrices Required high accuracy of sensed-to-model match Nonrigid nature of deformable tissues Implicit dependence on quality of sensing

7. Computer-Integrated Surgery (CIS)

8. CIS Information Flow Minimally invasive surgery (MIS) serves as model

9. Frame Transformations

10. Telesurgical Systems (I) Da Vinci � (Intuitive Surgical, Inc.)

11. Telesurgical Systems (II) System components such intent recognition and virtual fixtures for enhanced surgical assistance are currently in the research phase

12. Hidden Markov Model Intent Recognition Key component is the representation and learning of the sequential and temporal characteristics in activity sequences There is also an inherent hierarchical organization of activities and their typical duration

13. Precision Path Systems (I) Early systems such as CyberKnife (Accuray Incorporated) for stereotactic radiosurgery were used to stabilize the patient with respect to an instrument Closed loop control of the instrument was based on tracking of patient movement

14. Precision Path Systems (II) Path planning can be used for optimal insertion point and sequence of forces and torques (or velocities) to guide needle to target with minimal damage to surrounding tissue Real time image based control used for motion planning

15. Precision Positioning Systems (I) 6 Degree-of-Freedom (DoF) robot for needle placement while under guidance using CT or fluoroscopy Decoupled translational, orientational, and insertion movements Guided using joystick or touch screen

16. Precision Positioning Systems (II) Fiducial registration systems used for precision needle placement

17. Imaging, Modeling, & Analysis

18. Computer Vision Assisted Surgery (I) Method mitigates need for external tracking system Accuracy is well suited for tightly constrained environments such as transnasal zones Directly matches endoscopic video to 3D structure Mean closest distance error of 0.227mm Currently limited to offline processing

19. Computer Vision Assisted Surgery (II) Accurate matching to preoperative volumetric imagery hampered by need to extract motion of endoscopic camera from image derived feature points and rejection of outlier matched points (potentially up to 50%) ASKC (Adaptive Scale Kernel Consensus) estimator simultaneously estimates model parameters & scale of inliers Camera motion parameters estimated between video images using SIFT (Scale Invariant Feature Transform) feature point extraction coupled with SVD (Singular Value Decomposition) matching Model parameter estimate using a variable bandwidth kernel density estimate with residuals r is:

20. Modeling for Surgical Training Mockups used for training fixture Tracking of instruments same as that used in OR Graphical User Interface (GUI) gives feedback during mock operaion

21. Modeling for Planning & Results Analysis Previously used extensively in facial reconstructive surgery combining CT imagery and finite elements computer graphics Metrics have been defined for matching of results to plan for hard surfaces such as bone Differencing software for pre- and post-operative tumor removal procedures based on transformations of non-rigid structures is in common use

22. Interface Technologies

23. Haptic Feedback Systems Robotic telesurgery suffers from loss of sense of touch Two types are force and tactile Suturing task requires dexterity as well as tactile feedback Force feedback alone can�t be used to replicate accuracy of hand ties Still an open research area

24. Tremor Cancellation (I) Physiological tremor, drift, and nontremulous motion (e.g. myoclonic jerk) are three major components of inaccuracy in manipulation Telerobotic, �steady-hand� and handheld micromanipulator with active tremor cancellation are among methods to improve accuracy 88 neurosurgeons with varying experience participated in study to determine magnitude of tremor and drift related inaccuracies

25. Tremor Cancellation (II) Lower frequency components are order of magnitude larger than 10 Hz peak Handheld micromanipulator �Micron� with active tremor cancellation decreased power spectrum density by close to two orders of magnitude in 8-12 Hz range Surgeon must still support instrument during the operation

26. Augmented Reality Overlays Registration of model to live sensor feed is main constraint Overlay or laser guidance without obscuration of surgeon�s view is another constraint

27. Summary Sensor-based methods from ground and space robotics are useful in the medical robotics application areas Constraints on accuracy, speed, and size are driving factors that differentiate medical from industrial robotics Certification processes are in place but will need to evolve with increases in autonomy Operation such as that seen yesterday is beyond the capabilities of the current robotic systems

28. Backup Slides