Medical Robotics Classification of surgical systems

Universita di Roma “La Sapienza”

Medical Robotics

Classification of surgical systems

Marilena Vendittelli

• potential benefits

– coupling (real-time/on-line) information to action

– accuracy

– access to hostile (e.g., X-rays) or space-constrained areas (inside of a patient orimaging system)

– smaller targets

– not replacement but extension/augmentation of the medical staff capabilities

⇒ human-robot cooperation is one of the the central topics in medical robotics

• w.r.t. industrial robots, medical robots require specific safety measures, kinematics,hardware and software since they have to

– cooperate with the medical staff and accomplish tasks in contact with the patient

– posses application-specific functionalities

– be easily movable, not bulky, manually controllable

– accomplish non-repetitive tasks in unstructured environments

– be sterilizable and compatible with imagine systems

⇒ technological challenges in sensing, actuation, interfaces, system design

• technical paradigms

– different by degree of autonomy, type of provided support, type of access

M. Vendittelli Medical Robotics (Universita di Roma “La Sapienza”) – Classification 2

Classification 1(J. Troccaz, 2001)

• passive systems

provide information to the surgeon

• active systems: perform the procedure under human supervision

• interactive systems: mechanical guides

semi-active devices

synergistic devices

• teleoperated systems


passive system example

Viewing Wand(ISG Technologies)

• articulated arm with manually guidedprobe

• the probe position w.r.t. to the skull isused for– registration

– navigation

characteristics

• “tracking” of the object of interest

• stability of positioning if the arm is equipped with brakes

drawbacks

• tracking of only one object• cumbersome• constraints the surgeon motion• limited to navigation


active systems

• tasks with a complex geometry

– ROBODOC, CASPAR

• carry/hold heavy tools

– Cyberknife

• force controlled actions

– Hippocrate, SCALPP

• intra-body tasks

– EMIL

• moving targets

– Cyberknife + real-time patient tracking


ROBODOC

• SCARA maniplator with a 2dof wrist• 6D force/torque sensor• Orthodoc: planning system

example: hip surgery

1. planning with Orthodoc

2. pre-op to intra-op registration using implanted titanium pins

3. intra-operative bone milling procedure using ROBODOC


radiosurgery

traditional linear accelerator set-up

• complex trajectories for improved tumor destruction

• 6 dof required

• very heavy tools


Cyberknife

• 6MeV accelerator (1 eV= amount of kinetic energy gained by a single unbound electron when itaccelerates through an electrostatic potential difference of one volt)

• frameless neurosurgery

• small patient motion compensation

• large workspace


interactive systems

• principle: the robot constrains the surgeon’s action

• possible approaches

– semi-active: a mechanical constraint

– synergistic: a programmable mechanical constraint

• advantages

– man/machine cooperation (safety, psychological acceptance)

– rather direct interpretation of haptic data


semi-active systems

NeuroMate

• pre-positioning: robot

• surgical action: surgeon

• simple tasks– linear motions (e.g., needle insertion)

– planar motions (e.g., osteotomy)

– conical motions (e.g., laparoscopy)

• specific architecture


synergistic systems

• generalization of semi-active systems

• programmable mechanical guides

• different technologies

– programmable brakes (Taylor, P-TER, IMCAS)

– “nonholonomic coupling” of dofs (Cobot)

– windows of admissible velocities (PADyC)

– active Constraint ROBOT (Acrobot)


PADyC (Passive Arm with Dynamic Constraints)


freewheels

• one joint: two freewheels mounted in the opposite direction and actuated by twoindependent motors

F1: ω−i = 0 ∧ ω+i 6= 0 only ω+

user

F2: ω−i 6= 0 ∧ ω+i = 0 only ω−user

F3: ω−i 6= 0 ∧ ω+i 6= 0 both directions

F4: ω−i = 0 ∧ ω+i = 0 none

• ω−i and ω+i controlled by the computer, ωuser controlled by the user

• motion authorized for ω−i ≤ ωi ≤ ω+i


task constraints

• free mode: no constraint, the system computes and memorizes the position of thesurgical tool

• position mode: PADyC helps the user to move the tool towards a predefined positionand orientation (e.g., bone fragment or a prosthesis component)

• region mode: the tool is free to move in a given region of space, but cannot escapefrom that region (e.g., tumor resection or cavity preparation for prosthesis placement,avoidance of critical areas)

– keep inside

– keep outside

• trajectory mode: constrains the motion to follow a predefined trajectory with a givenaccuracy (e.g., biopsy trajectory)

• specialized modes

– linear motions

– planar motions

– conical motions


window of admissible configurations

regione

autorizzata

WAC(t)

Q(t)

q1(t)

q2(t)

q1(t)+!1+"t q1(t)-!1

-"t

q2(t)-!2-"t

q2(t)+!2+"t

example: 2R manipulator, region mode

given the robot configuration Q(t), the velocity constraints must be such that the configu-ration Q(t + ∆t) is contained in the admissible region


problem: mapping the task constraints to configuration constraints in real time

⇒ computation of WACj(t) for k control points on the surgical tool

WAC(t) = ∩kj=1WACj(t)


teleoperated systems

• daVinci

• Zeus


Classification vs function

domain of use

function

control modality

(strictly related to the degree of autonomy)

kinematicarchitecture

sensors and actuators

orthopedicsmachining

of rigid surface

cooperative or “hands-on”

MISconstrainedmanipulation

neurosurgery, intervantional radiology,

radiotherapy

constrainedtargeting

microsurgery micromanipulationshared/cooperative

control


Classification 2(Russel H. Taylor, 2003)

Computer Integrated Surgery (CIS)

surgical robotic systems are first part of CIS and then medical robots ⇒ they can beclassified according to their role in CIS systems


- patient modeling- planning- registration- execution- follow-up

advantages

- optimal planning- consistent and accurate execution- safety- validation- information management


examples

• robot assisted execution

– orthopedic prosthesis implant (ROBODOC)

– percutaneous therapy (NeuroMate)

• execution assisted by navigation systems

– therapy delivery with the aid of multi-modal images (Cyberknife)

– augmented reality (images overlay)


surgical extenders

– improve or extend surgeon’s abilities in manipulating surgical tools (e.g., tremorcancellation)

auxiliary surgical supports

– work side-by-side with the surgeon (e.g., endoscope holding or retraction)

advantages

- perform otherwise not possible procedures (e.g., beating heart surgery)- mortality and errors reduction- reduction of operating time- increased efficiency


examples

surgical extenders

– teleoperated systems (Zeus, daVinci)

– microsurgical systems (teleoperated or not, possibly without “manipulators”)

– cooperative systems

auxiliary surgical supports

– endoscopes, ecographic probes, . . ., controlled by the surgeon through variousinterfaces (AESOP)

– systems for intraluminal appilcations (active catheters, capsules)


Classification 3(L. Joskowicz, 2005)

computer assisted surgery support systems

• passive mechanisms

– adjustable frame/arm/support

– individual templates

• intraoperative imaging

• navigation

• robotics

– floor/bed mounted

– patient mounted


floor or bed-mounted

advantages

– integrated planning/execution

– intraoperative modifications

– rigid and accurate

drawbacks

– immobilization or tracking

– bulk, cost (EU 30 –500K)

– safety risk due to the large workspace and inertia


patient-mounted robot

advantages

– small size/footprint —minimal obstruction

– close proximity to surgical site

– no patient/anatomy immobilization, no tracking/real-time repositioning

– small workspace –fine positioning device

– potentially higher accuracy

– intrinsic safety due to small size/low power

drawbacks

– patient mount

– require manual coarse positioning


examples

spine surgery: pedicle screw insertion

recommended use

vertebra fracture

degenerative diseas

spine tumor

scoliosis


• individual template

advantages∗ inexpensive∗ rigid mechanical support∗ customized

drawbacks∗ requires manufacturing∗ no intraoperative changes∗ limited use: anatomy-dependent

• patient-mounted robots

MARS –Mazor Surgical Technologies, Israel


Classification 4(P. Dario, 2004)


Bibliography

O. Snider, J. Troccaz, “A six-degree-of-freedom Passive Arm with Dynamic Constraints(PADyC) for cardiac surgery application: Preliminary experiments,” Computer AidedSurgery, vol. 6, pp. 340–351, 2001.

P. Kazanzides, G. Fichtinger, G.D. Hager, A.M. Okamura, L.L. Whitcomb, R.H. Taylor,“Surgical and Interventional Robotics - Core Concepts, Technology, and Design,” IEEERobotics & Automation Magazine, vol. 15, no. 2, pp. 122–130, 2008.

R.H.Taylor, D. Stoianovici, “Medical robotics in computer-integrated surgery,” IEEETransactions on Robotics and Automation, vol. 19, no. 5, pp. 122–130, 2003.

M. Shoham, M. Burman, E. Zehavi, L. Joskowicz, E. Batkilin, Y. Kunicher “Bone-Mounted Miniature Robot for Surgical Procedures: Concept and Clinical Application-sy,” IEEE Transactions on Robotics and Automation, vol. 19, no. 5, pp. 893–901,2003.

M. Vendittelli Medical Robotics (Universita di Roma “La Sapienza”) – Classification: Bibliography 30

Medical Robotics Classification of surgical systems

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