The Centre of Image Guided Innovation and
Therapeutic Intervention (CIGITI)
The Hospital for Sick Children
University of Toronto, Canada
A Bi manual Neuroendoscopic Robot for intraventricular and Skull Base Surgery
James M. Drake FRCSC
11th SANS & 2nd APNS Annual Meeting Joint Conference Riyadh April 2017
Objectives
• Become familiar with the limitations of current neuro-endoscopic instrumentation and training
• Understand the currently available endoscopic simulators and their various advantages and uses.
• Discuss the potential role of robotic tools, informed by models, in advancing the range, efficacy, and outcomes of neuro-endoscopic procedures
Pre OP Post Op
Computer and Robotic Assisted Resection Thalamic Astrocytoma
Neurosurgery:1994, 34 (6) - p 1094-1097Instrumentation, Technique, and TechnologyISG Viewing Wand SystemDrake, James M.; Rutka, James T.; Hoffman, Harold J.
Technical Challenges2-3
– Tools limited to co-axial motion (2-DOF)
– Flexible endoscopes:
• Able to pitch up and down at distal end
• Difficult to maneuver by hand
• Reduced image quality
– Bimanual instrumentation difficult:
• Tools do not meet at a common point
• Tools obstruct view or clash with each other
• Need holder or assistant to position endoscope
– Endoscopes lack stereoscopic vision
Karl Storz LOTTA
Aesculap MINOP InVent
Karl Storz Neuro-Fiberscope
Technical Challenges2-3
• Difficult to address complex intraventricular pathology:
– Large, firm, vascular tumors
– Difficult-to-access location:
• Posterior third ventricle
• Temporal horn
– Multiple targets/procedures
• Combined pineal region tumor biopsy and ETV
• Choroid plexus cauterization
Schmidek & Sweet Operative Neurosurgical Techniques, 20124-5
Small exophytic tumourPosterior third ventricle? Metastatic CerebellarPilocytic Astrocytoma
6 yr old girl, intractable gelastic seizures, failed Gamma Knife treatment. Biggest challenge - “perfect” entry into ventricle – image guidance, ultrasound, etc
Concentric Tube Robots• Telescoping, pre-curved, superelastic nitinol tubes that when rotated/translated
relative to each other allows precise control of robot shape and position10
• “Snake-like” navigation along complex 3D pathways
Eastwood et al. 201511
Design Requirements
• Two arms, a camera and a suction device deployed through a 9-mm trocar
• High dexterity (>3DOF)
• Rated force: 0.5 N (required for brain tissue excision)
• Rated speed: 20 mm/sec and 12 rad/sec
• 40mm to 50mm reach
• Sub-millimeter accuracy
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Concentric-Tube Robot (CTR)
• Why?
– Optimum blend of dexterity and stiffness
– Simple to fabricate (miniaturize)
• Working principles
Each superelastic tube actuated by a linear as well as a rotary actuator
Aggregate shape controlled by tubes’ curvatures, stiffness and actuation
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System Overview
21
Slave Device
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Linear potentiometer
Rotary potentiometer
Left inner tube carriage
Left outer tube carriage
Right outer tube carriage
Right inner tube carriage
trocar
Grasper actuator
Scissors actuator
1. Trocar2. camera3. Right arm4. Left arm
ID (mm) OD (mm) Curvature (1/mm)
Inner tube 0.94 1.37 0
Outer tube 1.95 2.41 1/80
Interfacing
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QPID/QPIDe: PCIe-based Hardware-In-The-Loop (HIL) control boards ideal for control prototyping compatible with Matlab and Labview- High bandwidth- Optimized for real-time control- Analogue and digital input/outputs, built-in decoder for quadrature
encoders, 20MHz PWM
potentiometers
Analogue Input
Optical encoders
decoder
Analogue output
motor
Digital output
Simulator
• Simulator implemented using VRML in Matlab
• Useful for evaluating controller
• Helpful in hardware debugging
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Teleoperation
• Position control (rather than rate control)
• master workspace > slave workspace
• Virtual fixture (reactive force barrier) needed to prevent moving into prohibited areas
• Damping added for stability
25
Force barrier
Gravity compensation
damping
Performance: Dexterity and Reachability
Reachability (reachable workspace)
Dexterity: the ability to move the tip in various directions at any given point
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Stiffness > 2.4 mNm2
i.e. deflection < 5mm for F=0.5 NTip’s rated linear velocity= 20mm/secTip’s rated angular velocity= 12 rad/sec
Performance: Accuracy
- Tip positions within the workspace measured using NDI Aurora EM tracking system
- Sub-millimeter Sensor accuracy - 85% of data used for kinematic calibration
optimizing- Curvatures- Joint offsets- Registration error
- 15% used for validation
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Performance: Accuracy
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Left arm calibration residuals
Right arm calibration residuals
Left arm validation residuals
Right arm validation residuals
The Dexter Duo: Demonstration
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2X
Eastwood KW, Bodani VP, Drake JM. (2015). Three-Dimensional Simulation of Collision Free Paths for Combined Endoscopic Third Ventriculostomy and Pineal Region Tumor Biopsy: Implications for the Design Specifications of Future Flexible Endoscopic Instruments.Oper. Neurosurg.2015 In Press
H. Azimian, T. Looi, J. Drake,. (2015). The Dexter Duo: A Teleoperated Dual-Arm Robotic Neuroendoscope. IEEE Transactions on Mechatronics.
Conclusions
• The limitations in tools for intraventricular endoscopy preclude the surgical resection of most intraventricular lesions.
• Dextrous robotic tools are a potential solution, but pose a number of technical challenges related to minaturization
• Shape memory alloys employed as concentric tubes manipulators are a viable and robust solution.
• Attachment of standardized endoscopic tools has been implemented.
• Such robotic devices will still require manufacture and testing to regulatory standards.
• Implementation will require significant training and evaluation in which physical models may play an important role.
Conclusions
• Advances in this area will be particularly relevant to other areas of neurosurgery as well as other surgical specialties
• Demonstrating efficacy, in terms of improved clinical outcomes, will be critical, both for simulation training, and novel tools, to justify their investment and costs.
