This project is carried out in collaboration with the Department of Neuro-surgery in CHUV, Lausanne. The aim is to develop an active system to position and manipulate the surgeon’s tools during operations.
Our research is currently developing in two directions:
- A Robot Neuroglide for spinal surgery. The particular operation is positioning transarticular screws into vertebra C1 and C2.
System consists of:
- a miniature Neuroglide robot,
- a holding structure.
- A Haptic Guided ENT Force Guided Robot, as an extension of the Neuroglide robot functions.
Robot Assistant for Spinal Surgery
1 Project goals
The goal of the project is to build a medical robot capable of assisting the surgeon during screw placement operations in spinal surgery. The robot will hold and position a tube (trocar) according to a pre-defined screw trajectory .
2 Neuroglide Robot
This robot has been developed specially for surgical applications. It is highly compact, extremely rigid and very precise. Numerous other applications besides spinal screw placement, for example in ENT, and Orthopedics can be designed using add-on equipment that enhances the robot’s capabilities.
Characteristics of the Neuroglide:
- Working volume
- +/- 40mm in y,z
- +/- 7° for rotations
- High stiffness
- Measured precision (at the toolholder)
- +/- 25µm translation
- +/- 0.02° rotation
- Mechanical design
- no backlash
- rapid tool change
- Ear, Nose and Throat surgery
3 Spinal surgery process
- A 3D model of the spine is built based on the medical images of the patient. The same images are then used pre-operatively for planning the screw placement.
- The robot is positioned approximately.
- When commanded the robot automatically aligns the trocar with the predefined screw trajectory.
- The surgeon performs the entire screw placement through the positioned trocar and the robot compensates for any perturbations.
4 Results so far
Cadaver experiments have shown that the use of the Neuroglide considerably lowers spinal operation risks due to increased precision.
- More cadaver experiments for optimal precision
- Designing a second prototype (CE conform) for clinical trials.
Haptic Guided ENT Force Guided Robot
The goal of the project is to provide a robotic suite (including all the software & hardware modules ranging from the robotic platform up to user interface components) dedicated for Ear, Nose and Throat (ENT) surgery. ENT surgery requires both high dexterity and an extensive knowledge and expertise concerning the disease from the surgeon in order to obtain the best results. By combining Computer Assisted Surgery (CAS) techniques with robotics and keeping the user interface modules compatible with the surgical operating environment, we offer the surgeon a comfort level close to an open surgery in a minimally invasive environment. From a surgical point of view, the proposed development will lead to a robotic suite capable of Minimally Traumatic Surgery (MTS).
In standard operating procedures without navigation, the surgeon uses visual feedback to determine tool position. In practical terms this takes a lot of time and is not always possible. It leads to more invasive surgery, as larger incisions have to be made and substantially increases time in the operating room, the effort of the medical staff and trauma for the patient.
It would be a significant improvement if the surgeon had an integrated suite allowing him to navigate precisely relative to the patient. Surgery could be planned before and followed in the operating room. During surgery the surgeon could work in more comfortable conditions ans some of the inherent human defaults such as tremor could be removed. New sources of information, such as force, could be integrated. Extended logging could be carried out improving security and training purposes.
3.1 System components
The project is based on several key components developed separately and successfully tested in surgical environments. The project consists of integrating these modules and/or extending them to fit to technical and clinical requirements of the ENT robotic suite. A first version of the key components required to set up a haptic guided ENT force guided robot was completed in late summer 2010 and installed at the LSRO VRAI Group:
- 3 – 6 DOF haptic device
- 5 DOF robot
- 3DOF force sensor
- Planning Software
- Navigation Software
- UI modules (including multiple DOF input device)
The integration achieved so far was used as a proof of concept for the medical partners. Further work is required to propose a solution ready to be tested in the operating room.
3.2 Surgical work-flow
In the planning the surgeon should generate models for the “no-go” and “stay-in”zones. These correspond to volumes that should be protected during the surgery (like nerves, veins etc.) and removed (like tumours).
The tool used in the surgery (driller, shaver) should be fixed to the robot end effector. When the desired volumes are inside the robot’s workspace, the surgeon can control the robot position using the haptic device with the assistance from the navigation software. When approaching a “no-go” zone the surgeon feels a repulsive force on the haptic device that prevents him from violating important tissues. When he enters a “stay-in” zone he stays blocked inside until he explicitly wants to leave. He can move the tool inside the volume and follow the virtual tumour walls felt on the haptic device until he is sure to have removed all needed tissue. The margins of interaction with walls can be defined, so for example, it is possible to remove 80% of the tumour or 120% (tumour and surrounding tissues). The coupling between the haptic device and the robot movements can be defined so that the surgeon can have small movements with high precision or large movements with high speed.
Heavy bleeding is acceptable and does not disturb the robot’s operation (the robot and patient positions are measured by optical tracking so there is no need for an endoscope except for control and verification). As the tumour is removed rapidly (within a few minutes), heavy bleeding from the patient for a short time is acceptable.
New systems for haptic and force guided robotic surgery should significantly improve many aspects of neurosurgery. The surgery can be planned in advance in a precise manner and the surgeon defines which volumes he would like to remove and which should be protected. During surgery, the system using a haptic interface and force sensing ensures that the planning is executed. At each moment the surgeon can verify tool positions with reference to the patient on one of the graphical user interfaces. He can feel the forces applied to the surgical or palpation tools and is able to work in a comfortable position.
The newly developed system is desirable and solves important problems in ENT and neurosurgery that would be difficult to address otherwise. Future steps will involve medical tests in the operating room, on cadavers and eventually on patients.
Figure: Screenshot of the navigation software used in ENT surgery. The surgeon controls the tool position using the haptic device. He can feel repulsive forces as he approaches the “no-go” zones and can stay inside the “stay-in” zone until being sure to have removed all the needed tissue.
The system development is tested in partnership with Dr. John Duff (CHUV). An extension towards a semi-active tool holder is now running. This development is an undertaking co-financed by Co-Me and EPFL-LSRO.
People taking part in this project
|Baur||Charles||Director of VRAI group||ME B3 485||+41 21 693 78 12||charles (dot) baur (at) epfl (dot) ch||Info EPFL|
|Kostrzewski||Szymon||Assistant||ME H1 474||+41 21 693 65 78||szymon (DOT) kostrzewski (AT) epfl (DOT) ch||Info EPFL|
|Bérard||Philippe||Assistant||ME H1 474||+41 21 693 25 69||philippe (DOT) berard (AT) epfl (DOT) ch||Info EPFL|
|Derbanne||Tristan||Assistant||ME H1 474||+41 21 693 68 47||tristan (DOT) derbanne (AT) epfl (DOT) ch||Info EPFL|
|Fifański||Sebastian||Assistant||ME H1 474||+41 21 693 68 47||marc (DOT) weibel (AT) a3 (DOT) epfl (DOT) ch||Info EPFL|