A computer assisted method for guide-wore and catheter evaluation.

We developed a method for testing guide wires and catheters that realistically evaluates the forces applied to anatomical structures by these instruments during urological procedures. The placement of guide wires and catheters to gain access to the upper urinary tract can induce undesirable stress on the tissue. Previous studies have characterized wire/catheter performances base on their physical properties, such as stiffness and friction coefficient. However, the results of these studies do not directly quantify their effect on the tissues. Additionally, individual physical properties do not entirely characterize the behavior of the wire/catheter ensemble. Our model utilizes a computer-controlled test stand that simulates the urological environment by including a tortuous path and a stone obstruction. Experimental results indicate that the method shows significant promise in reflecting wire/catheter performance data in congruence with reliable real-life measures of stress upon relevant anatomical structures. Furthermore, due to the modularity of the approach, the model can be easily reconfigured to simulate environments from other medical fields.

Precision placement of instruments for minimally invasive procedures using a "needle driver" robot.

Medical practice continues to move toward less invasive procedures. Many of these procedures require the precision placement of a needle in the anatomy. Over the past several years, our research team has been investigating the use of a robotic needle driver to assist the physician in this task. This paper summarizes our work in this area. The robotic system is briefly described, followed by a description of a clinical trial in spinal nerve blockade. The robot was used under joystick control to place a 22 gauge needle in the spines of 10 patients using fluoroscopic imaging. The results were equivalent to the current manual procedure. We next describe our follow-up clinical application in lung biopsy for lung cancer screening under CT fluoroscopy. The system concept is discussed and the results of a phantom study are presented. A start-up company named ImageGuide has recently been formed to commercialize the robot. Their revised robot design is presented, along with plans to install a ceiling-mounted version of the robot in the CT fluoroscopy suite at Georgetown University.

Multi-imager compatible actuation principles in surgical robotics.

Today's most successful surgical robots are perhaps surgeon-driven systems, such as the daVinci (Intuitive Surgical Inc., USA, www.intuitivesurgical.com). These have already enabled surgery that was unattainable with classic instrumentation; however, at their present level of development, they have limited utility. The drawback of these systems is that they are independent self-contained units, and as such, they do not directly take advantage of patient data. The potential of these new surgical tools lies much further ahead. Integration with medical imaging and information are needed for these devices to achieve their true potential. Surgical robots and especially their subclass of image-guided systems require special design, construction and control compared to industrial types, due to the special requirements of the medical and imaging environments. Imager compatibility raises significant engineering challenges for the development of robotic manipulators with respect to imager access, safety, ergonomics, and above all the non-interference with the functionality of the imager. These apply to all known medical imaging types, but are especially challenging for achieving compatibility with the class of MRI systems. Even though a large majority of robotic components may be redesigned to be constructed of MRI compatible materials, for other components such as the motors used in actuation, prescribing MRI compatible materials alone is not sufficient. The electromagnetic motors most commonly used in robotic actuation, for example, are incompatible by principle. As such, alternate actuation principles using "intervention friendly" energy should be adopted and/or devised for these special surgical and radiological interventions. This paper defines the new concept of Multi-Imager Compatibility of surgical manipulators and describes its requirements. Subsequently, the paper gives several recommendations and proposes new actuation principles for this concept. Several implementations have been constructed and tested, and the results are presented here. This is the first paper addressing these issues.

Robotic assisted radio-frequency ablation of liver tumors--randomized patient study.

The minimally invasive treatment of liver tumors represents an alternative to the open surgery approach. Radio-frequency ablation destroys a tumor by delivering radio-frequency energy through a needle probe. Traditionally, the probe is placed manually using imaging feedback. New approaches use robotic devices to accurately place the instrument at the target. The authors developed an image-guided robotic system for percutaneous interventions using computed tomography. The paper presents a randomized patient study comparing the manual versus robotic needle placement for radio-frequency ablation procedures of liver tumors. The results of this study show that in our case robotic interventions were a very viable solution. Several treatment parameters such as radiation exposures and procedure-times were found to be significantly improved in the robotic case.

[Telerobotic surgery between Baltimore and Munich]. / Telerobotische Chirurgie zwischen Baltimore und München.

The rapid development of laparoscopy in urology necessitates the training of specialists to guarantee the high standard of patient care. The real-time data communication of medical information between physicians in different locations is known as telemedicine. Telementoring describes the assistance of an experienced surgeon, while telerobotics requires the use of robots. Two robots, the established AESOP and the PAKY + RCM developed at the Johns Hopkins Hospital (JHH), were used to perform a telerobotic laparoscopic renal cyst ablation in cooperation between Baltimore and Munich. The telementor maneuvered the robots over a distance of 8000 km using eight ISDN lines and a PC. AESOP moved the camera, while PAKY allowed the use of a fan retractor in the abdomen. The telerobotic operation was performed without complications or system and communication failures. Telementoring can be used for training purposes but also for consultation between specialists in emergency settings.

Measurement of bio-impedance with a smart needle to confirm percutaneous kidney access.

PURPOSE: The traditional method of percutaneous renal access requires freehand needle placement guided by C-arm fluoroscopy, ultrasonography, or computerized tomography. This approach provides limited objective means for verifying successful access. We developed an impedance based percutaneous Smart Needle system and successfully used it to confirm collecting system access in ex vivo porcine kidneys. MATERIALS AND METHODS: The Smart Needle consists of a modified 18 gauge percutaneous access needle with the inner stylet electrically insulated from the outer sheath. Impedance is measured between the exposed stylet tip and sheath using Model 4275 LCR meter (Hewlett-Packard, Sunnyvale, California). An ex vivo porcine kidney was distended by continuous gravity infusion of 100 cm. water saline from a catheter passed through the parenchyma into the collecting system. The Smart Needle was gradually inserted into the kidney to measure depth precisely using a robotic needle placement system, while impedance was measured continuously. RESULTS: The Smart Needle was inserted 4 times in each of 4 kidneys. When the needle penetrated the distended collecting system in 11 of 16 attempts, a characteristic sharp drop in resistivity was noted from 1.9 to 1.1 ohm m. Entry into the collecting system was confirmed by removing the stylet and observing fluid flow from the sheath. This characteristic impedance change was observed only at successful entry into the collecting system. CONCLUSIONS: A characteristic sharp drop in impedance signifies successful entry into the collecting system. The Smart Needle system may prove useful for percutaneous kidney access.

URobotics--Urology Robotics at Johns Hopkins.

URobotics (Urology Robotics) is a program of the Urology Department at the Johns Hopkins Medical Institutions dedicated to the development of new technology for urologic surgery (http://urology.jhu.edu/ urobotics). The program is unique in that it is the only academic engineering program exclusively applied to urology. The program combines efforts and expertise from the medical and engineering fields through a close partnership of clinical and technical personnel. Since its creation in 1996, the URobotics lab has created several devices, instruments, and robotic systems, several of which have been successfully used in the operating room. This article reviews the technology developed in our laboratory and its surgical applications, and highlights our future directions.

System for robotically assisted percutaneous procedures with computed tomography guidance.

We present the prototype of an image-guided robotic system for accurate and consistent placement of percutaneous needles in soft-tissue targets under CT guidance inside the gantry of a CT scanner. The couch-mounted system consists of a seven-degrees-of-freedom passive mounting arm, a remote center-of-motion robot, and a motorized needle-insertion device. Single-image-based coregistration of the robot and image space is achieved by stereotactic localization using a miniature version of the BRW head frame built into the radiolucent needle driver. The surgeon plans and controls the intervention in the scanner room on a desktop computer that receives DICOM images from the scanner. The system does not need calibration, employs pure image-based registration, and does not utilize any vendor-specific hardware or software features. In the open air, where there is no needle-tissue interaction, we systematically achieved an accuracy better than 1 mm in hitting targets at 5-8 cm from the fulcrum point. In the phantom, the orientation accuracy was 0.6 degrees, and the distance between the needle tip and the target was 1.04 mm. Experiments indicated that this robotic system is suitable for a variety of percutaneous clinical applications.

Remote percutaneous renal access using a new automated telesurgical robotic system.

Previous clinical application of remote telesurgery has been the use of a novel system of video teleconferencing equipment along with remote control of a laparoscopic camera at distances over 11,000 miles. Recently, a robotic system has been developed to assist with percutaneous renal surgery. This robot has been incorporated into the telesurgical system to allow remote needle placement into the renal collecting system under radiological guidance. The main component of the telesurgical system is a low degree of freedom robot called "PAKY" (percutaneous access of the kidney). It is custom designed for fluoroscopic guided percutaneous needle insertion into the renal collecting system. The robot is a six-degrees of freedom device. However, when the skin entry site is fixed and held in position, only two degrees of freedom are required to orient the needle in the correct plane for accurate insertion. Remote control of the robot was accomplished over a plain old telephone system (POTS) line. On June 17, 1998, the first remote telerobotic percutaneous renal access procedure was performed between the Johns Hopkins Hospital, Baltimore, Maryland, and Tor Vergata University, Rome, Italy. This new telesurgical robot was successful in term of obtaining percutaneous access within 20 min, with two attempts to obtain entry into the collecting system. This robot represents the first system for performing remote telesurgical interventions in the kidney and demonstrates the feasibility and safety of assisting accurate and rapid needle access to the kidney during percutaneous procedures.

Robotic surgery.

The industrial revolution demonstrated the capability of robotic systems to facilitate and improve manufacturing. As a result, robotics extended to various other domains, including the delivery of health care. Hence, robots have been developed to assist hospital staff, to facilitate laboratory analyses, to augment patient rehabilitation, and even to advance surgical performance. As robotics lead usefulness and gain wider acceptance among the surgical community, the urologist should become familiar with this new interdisciplinary field and its "URobotics" subset: robotics applied to urology. This article reviews the current applications and experience, issues and debates in surgical robotics, and highlights future directions in the field.

Effect of time delay on surgical performance during telesurgical manipulation.

BACKGROUND: Telementoring allows a less experienced surgeon to benefit from an expert surgical consultation, reducing cost, travel, and the learning curve associated with new procedures. However, there are several technical limitations that affect practical applications. One potentially serious problem is the time delay that occurs any time data are transferred across long distances. To date, the effect of time delay on surgical performance has not been studied. MATERIALS AND METHODS: A two-phase trial was designed to examine the effect of time delay on surgical performance. In the first phase, a series of tasks was performed, and the numbers of robotic movements required for completion was counted. Programmed incremental time delays were made in audiovisual acquisition and robotic controls. The number of errors made while performing each task at various time delay intervals was noted. In the second phase, a remote surgeon in Baltimore performed the tasks 9000 miles away in Singapore. The number of errors made was recorded. RESULTS: As the time delay increased, the number of operator errors increased. The accuracy needed to perform remote robotic procedures was diminished as the time delay increased. A learning curve did exist for each task, but as the time delay interval increased, it took longer to complete the task. CONCLUSIONS: Time delay does affect surgical performance. There is an acceptable delay of <700 msec in which surgeons can compensate for this phenomenon. Clinical studies will be needed to evaluate the true impact of time delay.

The EndoHand: comparison with standard laparoscopic instrumentation.

Laparoscopic instrumentation is constantly being refined in an attempt to achieve the proficiency, flexibility, and tactile feedback that would be available if the human hand were small enough to be used in laparoscopic surgery. The EndoHand (DAUM GmbH, Schwerin, Germany) is a novel laparoscopic three-fingered hand developed as an advancement over standard laparoscopic tools. Grasping and manipulation ability, dexterity, and tactile feedback were compared with those of current laparoscopic instrumentation. Experiments included measurement of achievable angles of approach to a fixed point behind a 2-cm-tall obstruction, completion time and error rates during a pelvic trainer dexterity task, and tactile feedback using a device invented to simulate tissue resistance. Subjectively, the EndoHand was able to pick up a range of objects similar to those graspable by a Babcock clamp. More complex types of manipulation were possible with the EndoHand because of its wrist joint. The range of approach angles to the fixed point was 35 degrees to 90 degrees with the EndoHand and 70 degrees to 90 degrees with the straight instruments. The dexterity of the EndoHand was significantly less than that of the other two instruments, as measured by time (P = 0.0002) and errors (P = 0.02). Standard instruments were also more accurate in the tactile feedback trials (P = 0.02). The EndoHand is a prototype of a unique new generation of laparoscopic instruments. Although it falls short in both dexterity and tactile feedback, significant promise is shown in its ability to perform sophisticated manipulation of objects and its flexibility to work at a larger range of angles to the target tissue. The EndoHand may be most useful on the nondominant hand of the surgeon to assist with positioning and holding tissue in a specific orientation. Clinical trials will determine its eventual role in laparoscopic surgery.

Telemedicine and surgical robotics: urologic applications.

Medical treatment can be improved through integration and application of advances in technology, computers, and engineering. Accuracy and reliability are essential characteristics of any mechanical system, and with the evolution of machines capable of precise movements, the integration of medicine and machine is achievable. Early mechanical devices were effective in performing simple, repetitive tasks but were not sophisticated enough for independent function. In the automobile industry, robots could work on the assembly line executing these cyclic tasks. These machines could execute simple, reiterative movements without integrating new information from the environment. In this day and age, robots have evolved into sophisticated mechanical devices that can "react" to data detected in the environment to determine the next course of events. They have evolved from the assembly line to the operating room, assisting surgeons during surgery to participating in remote telesurgical procedures.

Stereotactic mechanical percutaneous renal access.

Obtaining accurate percutaneous renal access when treating intrarenal disease requires substantial skill. Robotic devices have been used in a variety of surgical applications and have been successful in facilitating percutaneous puncture while improving accuracy. Laboratory models of robotic devices for percutaneous renal access have also been developed. However, several technical hurdles need to be addressed. One relates to the device-patient interface. As a first step in creating a complete robotic system, a mechanical arm (PAKY) with active translational motion for percutaneous renal access has been developed and clinically assessed. The PAKY consists of a passive mechanical arm mounted on the operating table and a radiolucent needle driver that uses a novel active translational mechanism for needle advancement. The system utilizes real-time fluoroscopic images provided by a C-arm to align and monitor active needle placement. In vitro experiments to test needle placement accuracy were conducted using a porcine kidney suspended in agarose gel. Seven copper balls 3 to 12.5 mm diameter were placed in the collecting system as targets, and successful access was confirmed by electrical contact with the ball. The PAKY was then used clinically in nine patients. The number of attempts, target calix location, calix size, and time elapsed were evaluated. In the in vitro study, successful needle-ball contact occurred the first time in all 70 attempts, including 10 attempts at the 3-mm balls. Clinically, percutaneous access to the desired calix was attained on the first attempt in each case. The mean target calix diameter was 14.7 mm (range 7-40 mm). The mean time elapsed while attempting access was 8.2 minutes. No perioperative complications attributable to needle access occurred. Early experience indicates that the PAKY provides a steady needle holder and an effective and safe end-effector for percutaneous renal access. This device may provide the mechanical platform for the development of a complete robotic system capable of creating percutaneous renal access.

Robotic surgery in urology.

The demand for improved surgical performance and reduced health care costs have led to the evaluation of surgical robotic systems. Robotic devices to assist urologists with transurethral resection of the prostate, percutaneous renal access, and laparoscopy are currently in development or are already in clinical use. The rapid advances made in telecommunication technology also have allowed for the development of telesurgical systems that permit surgeons to participate in surgery from a remote location. In the twenty-first century, surgical robots will be efficient, invaluable, and safe adjuncts to urologic practice.

Kinematics and dynamic stability of the locomotion of post-polio patients.

The study reported in this article was conducted to propose a set graphical and analytical tools and assess their clinical utility by analyzing gait kinematics and dynamics of polio survivors. Phase-plane portraits and first return maps were used as graphical tools to detect abnormal patterns in the sagittal kinematics of post-polio gait. Two new scalar measures were introduced to assess the bilateral kinematic symmetry and dynamic stability of human locomotion. Nine healthy subjects and seventeen post-polio patients were involved in the project. Significant increases in the knee extension and ankle plantar flexion of post-polio patients were observed during the weight acceptance phases of their gait. Polio patients also exhibited highly noticeable excessive hip flexion during the swing phase of their ambulation. Using the proposed symmetry measure, we concluded that post-polio patients walked less symmetrically than normals. Our conclusion, however, was based on the bilateral symmetry in the sagittal plane only. Finally, we observed that post-polio patients walked significantly less stably than normals. In addition, weaknesses in lower extremity muscles of polio patients were found to be an important factor that affected stable ambulation.