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TECHnOLOGY

RoboticsRevolutionizing urologic surgery

By Dan Stoianovici, PhD

Though not yet commonplace. robotic systems are

appearing with increasing frequency in the operating

room and are gaining wider acceptance by the surgical

community. An examination of the current state of

robotics in urology shows its ability to improve eXisting

operative techniques and its promise for future advances.

To many, the idea of computer­dliven robots performing sur­gery seems fantastic, bring­

ing to mind the "mecha"ractersfioom Steven Spielberg's recent sci­ence fiction movie AT. In reality,however, a number of robotic sys­tems have been evaluated in clinical

trials, and some-having demon­strated their clinical utility and abil­ity to enhance surgical perfor­mance-have received Food andDrug Administration (FDA) ap­proval and are now commerciallyavailable.

Unfortunately, urologic surgeonshave not embraced robots as enthu­siastically as their colleagues in or­thopedics and neurosurgery-oreven cardiology'! Although OIthope­die surgeons and nem'osurgeons pio­neered the use of surgical robotics inthe 1980s, they had the advantageof having simpler requirements for

their robotic systems-the organsthat were to be operated on could beimmobilized and had reduced de­formability. Conversely, systemsused for soft tissue operations, suchas those pelfol1lled in urology, re­quire very sophisticated robotic re­sponsiveness and computer control

awareness to adapt to the defol1lla­bility and mobility of the organs.While these difficulties delayedthe progress of urology robotics(URobotics), several systems applic­able to urology, including smogeon­dJ.~ven robots and robots developedspecifically for urologic applications,have nonetheless been developed orare cmTently under development.

As "mechatronic" technology ad­vances, the capabilities of surgicalrobots are evolving as well, en­abling them to perform less inva­sive procedures with increasing au­tonomy. Dri ving this technology

are 2 clear advantages that robotsoffer over humans: the ability to op­erate based on digital infol1llation,which pemuts precise image-basedtargeting; and outstanding motioncapabilities, which allows for im­proved, minimally invasive access.To date, however, computer visionand image interpretation remainmajor limiting factors.

How they work

Robots are mechanical systemsthat are controlled by microproces­sors and are equipped with sensorsand motorso Computer algorithmsuse the environmental infonnationprovided by the sensors and the in­put of the operator to impose ap­propriate motor commands, en­abling the mechanical system toperform a desired task. In surgicalrobotics, a task can be predefinedby the surgeon based on preopera­tive or interventional data, or it canbe defined at smogery when, due toits complexity, the dynamics of thetask cannot be set prior to the oper­ation. There are 2 main categoriesof surgical robots: image-guidedand surgeon-dJ.~ven systems.

Image-guided robotic systems

These systems are used in radiolog­ic interventions (such as percuta­neous needle access) to guide and,

Dr. Stoianovici is Assistant Professor of Urology and Mechanical Engineering, and Director, URobotics Program,James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, Md.

Under a licensing agreement between ImageGuide Inc. and the Johns Hopkins University, Dr. Stoianovici is entitled toa share of royalty received by the University on sales of the ReM and Tracker robots described in this article.Dr. Stoianovici and the University are also shareholders in ImageGuide Inc.

58 CONTEMPORARY UROLOGY. OCTOBER 2002

ROBOTIC SURGERY

The needle in the driver can be oriented andinserted robotically under C-arm guidance.

FIGURE 1

PAKY-RCM robot

sometimes, to insert an in­strument or pl'obe into thebody. These systems typical­ly act as trajectory-enforce­ment devices that are usedin conjunction with C-armand biplanar fluoroscopy, ul­trasonography (US), or com­puted tomography (CT) andmagnetic resonanc-e imaging(MR I) scanners.2 Image­guided systems take advan­tage of the robot's ability touse digital coordinate infor­mation provided by the im­ager to manipulate instru­ments in the physical spaceof the patient. This type ofinstmment manipulation can be ac­complished with greater accuracythan manual placement using image­space feedback.

The first purpose-built, image­guided robot for urology was intro­duced in 1989 by a group at TheImpel;al College in London3 It wasdesigned to perform transurethralresection of the prostate because ofthe relatively fixed position of theprostate and because the procedw'erequires the pe.rfol1nance of repeti­tive movements in a geometric pat­tern."" In 5 clinical hials, the robotautomatically generated a sequenceof overlapping cuts in successivelylarger rings. staJting at the hypo­thetical bladder neck. TJ;als iden­tified that, at that time, US wasinsufficiently accurate for robotcontrol.··6 Although not absolutelysuccessful, this system was the firstrecorded autonomous robotic sur­gery in humans-and the firstURobot.X-ray guidallce. The group at TheImpmial College also created a ro­botic system to assist with intraop­erative percutaneous renal access.7

They employed a passive encoded,mn equipped with electromagnetic

brakes mounted to the operatingtable. The access needle was manu­ally positioned as prescdbed by acomputer that triangulated the cal­yceal location from multiple C-mmx-rays." In vitro experiments eval­uating system performance dem­onstrated its accuracy, positioningthe needle less than 1.5 mm fromthe taJ-get.

In 1996, the URobotics programat Johns Hopkins in Baltimore alsodeveloped a robotic module for pel'­

cutaneous access of the kidney(pAKY).9 This module is an activeand radiolucent needle driver,which was initially SUppolted by apassive arm. lo The needle in thedriver was manually positionedunder C-arm guidance, and oncelocked in place, needle insertionwas performed automatically bya surgeon controlling a joystick.PAKY has been used successfullyin numerous clinical cases, althoughthe proceclw-e essentially remainedmanually guided. II The main ad­vantage of PAKY was that it heldthe needle and locked its trajectory,allowing the surgeon's hands to re­main out of the x-ray field dw;nginsmtion.

Needle orientation wasautomated with the additionof the remote center of mo­tion (RCM) module (Image­Guide Inc, Baltimore, Md),which SUppOltS and OI;entsthe PAKY driver while main­taining the fixed location ofthe needle tip (Figw'e 1).12Known as PAKY-RCM, thissystem allows for robotic od­entation and inseltion of theneedle using various x-rayguidance procedures. Thesystem, which has been usedextensively for percutaneousrenal access at Johns Hop-kins, offers improved needle

placement accuracy, a shortenedprocedure time, and reduced radia­tion exposure to the patient and theurologist.II PAKY-RCM can inte­grate C-arm software and uses"Fluoro-Serving" image registra­tion and guidance software to auto­matically place the needle at thetaJ'geted image, which is pointed to

. by the urologist using a mouse.13

The PAKY-RCM has been used inseveral transatlantic telesurgicalcases.14

CT-guidallce. A simple method forrobot registration, laser-basedCTIMR registration, was also de­veloped in ow' URobotics laborat()­ry to allow the PAKY-RCM systemto be used under CT guidance.I.The registration method uses thelaser markers readily available onany CT scanner and does not re­quire the surgeon to be adjacent tothe patient, thus eliminating radia­tion exposw·e. The system (Figw-e2) has been used successfully formultiple CT-guided biopsy and ra­diofrequency (RF) ablation proce­dures on the kidney and spine andfor nephrostomy tube placement.16

Tracker (ImageGuide Inc), ourmost recent robotic system, was

60 CONTEMPORARY UROLOGY· OCTOBER 2002

ROBOTIC SURGERY

at the University of Tokyodeveloped an MR-compati­ble needle inseltion manipu­lator using ultrasonic actua­tion and tested it on phantommodels."' Researchers at theBl1gham and Women's Hos­pital in Boston, in collabo­ration with the Agency forIndust11al Science and Tech­nologylNlinistry of Interna­tional Trade and Industryin Japan, are developing anovel system composed ofa 5-DOF manipulator and a"double donut" open MRscanncl'.22 The robot is lo-cated between the verticaldonuts above the surgeon's

head and presents 2 long mms thatextend into the imaging regionclose to the patient. The system isdesigned to serve as an image­guided surgical assistant, integrat­ing preoperative planning and in­traoperative lVIRI.

MicRo, a multi-imager compati­ble robot lmder development in ourlabOl-atory, is designed to help ob­tain precise percutaneous prostate

Left: Touch-screen controller. Right: Robot, consisting of RCMmodules, a passive positioning arm, and an XYZ translational stage,all mounted on a bridge-like support. This system was specificallydeveloped for CT-guided percutaneous procedures.

FIGURE 3

Tracker robot mounted on CT scanner

ance is also under development,and an evaluation on phantom mod­els was considered successful.1!lMR gnidance. The development ofan MR-compatible rohotic systemis at the forefront of image-guidedresearch. Hynynen and colleaguesdeveloped an MR-guided systemfor noninvasive surgery withhigh-intensity focused ultrasound(HIFU).ro Masamune and colleagues

Laser-based CT/MR registration allows thePAKY-RCM system to be used under CTguidance.

FIGURE 2

PAKY-RCM robot in CT-guidednephrostomy tube placement

specifically developed for CT­guided percutaneous proce­dures (Figure 3)17 Its name"-as derived from its abilityto actively track respiratoryand other soft tissue motion.Tracker can precisely manip­ulate needles and other sm-gi­cal instruments in the con­fined space of the imager"ithout interfellng ",th im­age quality.

Tracker is ('Onnccted to themobile table of the CT, allow­ing the patient and the robotto be sent togethel' into theCT gantry for imaging andintcl'ventional procedures.The system is composed ofthe PAKY and RCM l'obotic mod­ules, a new passive po~itioning aIm,and a translational stage, which al­lows an active 3 degrees of freedom(DOF), all mounted on a btidge-IikeSUPPOlt. A touch-screen display anda joystick are mounted on the mbot.Investigators at Georgetown Med­ical Center in Washington. DC, willsoon begin clinical evaluation of theTracker system.US guidance. Another image-guid­ed robot that has been e\-aluatedclinically was developed at thePolitecnico or Milan, Italy to per­form trans perineal prostate bi­op8ie,.17·18 Using transrectal US('l'HU;;), this system can accm-ate­Iy po,ition the needle within 1 to2 nun of the target. With this sys­tem, the surgeon chooses the bi­opsy site from the TRUS images,and the robot obtains the sample.While the robot demonstrated in­creased accuracy compared withthe manual procedUl'e, broad clini­cal use of tllis system has been lim­ited clue to increased set-up timeand expense.

A system that performs prostatebrachytherapy under TI,US guid-

OCTOBER 2002 • CONTEMPORARY UROLOGY 63

ROBOTIC SURGERY

Left: The daVinci robotic system consists of a 3-arm robotic unit.Right: Surgeon-operated control console.

FIGURES

daVinci robotic system

This surgeon-driven instrument manipulation system, whichwas designed for open surgical procedures, includes a 2-arm,high-mobility robot instrumented with grippers.

of the instl1lments manipulated bythe robot. In robotics terminology,this is referred to as master-slavesystem architecture. These sys­tems combine the fine manipulationcapabilities of a robotic system withthe surgeon's perception and judg­ment, allowing for scaled down,steady, tremor-free motion. ThesW'geon is located away from theoperative field, which permits ac­cess to confined spaces dwing mini­mally invasive procedures and of­fers the ability to perform telesw'­gical procedures.Zl

Most sw-geon-driven robotic sys­tems have been created for genera)laparoscopic use. They include ma­nipulator arms that help the sur­geon increase manual dexterity andperform tasks such as positioningthe laparoscope.AESOP. The fu-st surgical robot toreceive FDA clearance was the Au­tomated Endoscopic System forOptimal Positioning (AESOP,Computer Motion Inc, Goleta,Calif). AESOP is one of the sim­plest types of surgeon-chiven sys­tems because its only function is tohold and olient a laparoscopic cam­era under hand, foot, or voice con­trol. The robot has been used atseveral institutions and in manyclinical areas, including urologiclaparoscopy.24 Kavoussi and associ­ates found that the camera was sig­nificantly steadier under robot con­trol, and neither operative set-upnor breakdown time was increasedwith the use of the robotic assis­tant.""SRI. The first surgeon-chiven in­stl1lment manipulation system wasdeveloped at the Stanford Re­search Institute (SRI) in MenloPark, Calif for use dwing open sw'­gical procedures. This system,which is operated from a console,includes a 2-arm, high-mobility ro-

Surgeon-driven robotic systemsThese systems complise specializedinput devices from which the sur­geon directly controls the motion

FIGURE 4

SRI teleoperation system for open surgicalprocedures

access for minimally invasive thera­pies. This robot has a novel MR­compatible motor that uses hy­draulic energy.

64 CONTEMPORARY UROLOGY. OCTOBER 2002

bot instrumented with grip-pers (Figure 4). Cornum andBowersox used the system forin vivo porcine nephrectomyand the repair of bladder anduretlu-al injwies.26

daVillci. Perhaps the most suc­cessful sw-gical robot today isthe "daVinci" laparoscopic m­bot system (Intuitive Sw-gicalInc, Mountain View, CaliD.Like the SRI robot, this sys­tem (Figure 5) has a contmlconsole that is opemted by thesurgeon and a 3-arm roboticunit (2 arms for instrumentmanipulation and 1 for the la­paroscope). Pencil-sized instru­ments, such as needle holders,scissors, dissectOl'S, and scalpel,are equipped with a wrist toprovide additional dextelity.27Several European centershave used daVinci to perfOlmlaparoscopic cardiac bypasssurgery without cardiopul­monaJy bypass. The daVinci systemreceived FDA cleaJW1ce in 2001 andis presently being used in most ma­jor clinical cente.'S across the coun­t1y. The range of uses for tl,e daVin­ci system includes a nwnbe.· of uro­logic applications and is constantlyexpanding.Zeus. The most successful telesur­gical operation to date was "Opem­tien Lindbergh," which was per­formed in September 2001 usingthe Zeus robotic system (ComputerMotion Inc) for laparoscopic sur-

REFERENCES

1. Stoianovici D. Robotic surgery. World JUral.2000,18(4).2890295.

2. Stoianovici D, Cadeddu JA, Kavoussi LR. Uro­logic applications of robotics. AUA Update Series.1999:18(25):194-200.3. Davies BL, Hibberd AD. Coptcoat MJ, et at Asurgeon robot prostatectomy-a laboratory eval­uation. J Med Eng TechnoJ. 1989:13(6):273-2774. Davies BL, Hibberd AD, Ng WS, et al. The de­

velopment of a surgeon robot for prostatectomiesProc Inst Mech Eng (H). 1991 :205(1):35-38

FIGURE 6

Zeus robotic system

A bilateral console allows the surgeonto operate the Zeus system.

gery. The surgeon, who was inNew York, performed a laparo­scopic gall bladder operation on apatient in Strasbourg, France. TheZeus system, which C'dn also be op­eratedlocally, consists of3 modifiedAESOP robots-1 for the laparo­scope and 2 for the instl1lments­and a bilateral sUl"geon's console(Figure 6). The system has not yetreceived FDA approval. Compared"ith daVinci, Zeus requires signifi­cantly less preoperative setup.However, Zeus is currently less

S. Nathan MS. Davies BL. Hibberd RD, et al De­vices for automated resection of the prostate.Proceedings First International Symposium onMedical Robotics and Computer Assisted Surgery.1994:342-344.

6. Ng WS, Davies BL. Timoney AG, et aL The useof ultrasound in automated prostatectomy. MedBioi Eng Comput. 1993:31(4):349-354.

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ROBOTIC SURGERY

maneuverable than da Vinci.This is primarily because Zeususes AESOP robots Oliginallydesigned for camera holding,while daVinci was purposelydesigned for a master-slaveopemtion.

Conclusion

Surgical robotics opens "idethe possibility of improvingexisting operative techniquesand performing new pmce­dures. Among many other ad­vantages, robots allow formore precise manipulation ofsurgical instruments com­pared with manual proce­dures. Digital mapping of thepatient by sophisticated imag­ing equipment can allow forautonomous control.

Several surgical robotshave been developed and test­ed, and some have demon­strated clinical utility. With

continued hardware and softwareimprovements, the applications forsurgical robotics will only expand,opening new horizons for m·ologicpractice.

Acknowledgement

Some of the work presented was partiallysupported by gran. No. 1R21 GA088232­01 A1 from the National Cancer Institute(NGI). This article's con'ents are soelythe responsibility of the authors and donot necessarily represent the officialviews of NeL

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