We have developed and validated a new tendon-driven continuum robot for neuroendoscopy. The tendon-driven continuum robot has the outer diameter of 3.4 mm and two bending sections. We have also newly introduced an extended forward kinematic mapping (FKM) with attention to the hysteresis operation of the robot. The extended FKM maps tension in tendons to the posture of the robot as time discrete valuables, and evolves the previous posture to the present posture. Through this computation process, the extended FKM performs mapping with the hysteresis. We conducted articulation experiments with the tendon-driven continuum robot to test the extended FKM. We measured the postures reached from two different initial postures as the hysteresis operation, and assessed the prediction accuracy of the postures in comparison to the FKM in our previous study. In the experimental results, the extended FKM predicted the postures in the hysteresis operation with improved accuracy (the maximum position error: 1.6 mm by the extended FKM vs. 3.5 mm by the FKM over 60 mm articulation length).

This article addresses the two key challenges in computer-assisted percutaneous tumor ablation: planning multiple overlapping ablations for large tumors while avoiding critical structures, and executing the prescribed plan. Toward semiautomatic treatment planning for image-guided surgical interventions, we develop a systematic approach to the needle-based ablation placement task, ranging from preoperative planning algorithms to an intraoperative execution platform. The planning system incorporates clinical constraints on ablations and trajectories using a multiple objective optimization formulation, which consists of optimal path selection and ablation coverage optimization based on integer programming. The system implementation is presented and validated in both phantom and animal studies. The presented system can potentially be further extended for other ablation techniques such as cryotherapy.

This paper undertakes the modular design and development of a minimally invasive surgical manipulator for MRI-guided transperineal prostate interventions. Severe constraints for the MRI-compatibility to hold the minimum artifact on the image quality and dimensions restraint of the bore scanner shadow the design procedure. Regarding the constructive design, the manipulator kinematics has been optimized and the effective analytical needle workspace is developed and followed by proposing the workflow for the manual needle insertion. A study of the finite element analysis is established and utilized to improve the mechanism weaknesses under some inevitable external forces to ensure the minimum structure deformation. The procedure for attaching a sterile plastic drape on the robot manipulator is discussed. The introduced robotic manipulator herein is aimed for the clinically prostate biopsy and brachytherapy applications.

MRI-guided percutaneous liver interventions have been investigated by researchers as an alternative to CT-guided procedures as it is non-invasive and provides greater soft tissue details. In practice, however, repeated needle insertion is still required to reach desired positions on trial-and-error basis. To minimize the needle attempt and procedural time, we designed a robotic needle guidance device that provides needle insertion angle guidance at skin entry using two rotational joints structured for remote-center-of-motion manipulation. To evaluate the mechanism and clinical feasibility, we fabricated a proof-of-concept prototype that can be manually operated. As preliminary design evaluation, we conducted a retrospective clinical study of 13 MRI-guided abdominal biopsies to determine if the proposed mechanism and device can provide necessary needle insertion angles in MRI-guided liver biopsy procedures. The number of needle insertion attempts per biopsy was also measured. To confirm the kinematic design of the double ring remote-center-of-motion mechanism and to identify any procedural difficulties, we conducted a phantom targeting experiment. The retrospective clinical study showed that the 80 degree insertion angle coverage of the device is sufficient for clinical cases, and an average of five needle insertion attempts per biopsy in conventional MRI-guided biopsy can be reduced by the proposed device. A phantom targeting experiment confirmed that the unique kinematic design was successfully implementation in the targeting.

Magnetic Resonance Imaging (MRI) guided prostate biopsy and brachytherapy has been introduced in order to enhance the cancer detection and treatment. For the accurate needle positioning, a number of robotic assistants have been developed. However, problems exist due to the strong magnetic field and limited workspace. Pneumatically actuated robots have shown the minimum distraction in the environment but the confined workspace limits optimal robot design and thus controllability is often poor. To overcome the problem, a simple external damping mechanism using timing belts was sought and a 1-DOF mechanism test result indicated sufficient positioning accuracy. Based on the damping mechanism and modular system design approach, a new workspace-optimized 4-DOF parallel robot was developed for the MRI-guided prostate biopsy and brachytherapy. A preliminary evaluation of the robot was conducted using previously developed pneumatic controller and satisfying results were obtained.

Magnetic Resonance Imaging (MRI) has potential to be a superior medical imaging modality for guiding and monitoring prostatic interventions. The strong magnetic field prevents the use of conventional mechatronics and the confined physical space makes it extremely challenging to access the patient. We have designed a robotic assistant system that overcomes these difficulties and promises safe and reliable intra-prostatic needle placement inside closed high-field MRI scanners. The robot performs needle insertion under real-time 3T MR image guidance; workspace requirements, MR compatibility, and workflow have been evaluated on phantoms. The paper explains the robot mechanism and controller design and presents results of preliminary evaluation of the system.

Capsule endoscopy is a promising technique for diagnosing diseases in the small intestines. Here we propose a miniature swimming mechanism that uses MRI’s magnetic fields for both propulsion and wireless energy delivery. Our method uses both the static and radio frequency (RF) magnetic field inherently available in MRI to generate propulsion force. The propulsion force is produced by a swimming tail containing waving beam consisting of three coils in a row. Alternating current in the coils acting on the static magnetic field of the MRI will generate waving movement to produce a propulsion force. RF magnetic field will provide power to generate the alternating currents in the coils. We developed a theoretical model to predict sinusoidal waves produced by the waving beam using the Euler-Bernoulli beam equation and multiple-input multiple-output system were solved using antenna design theory. This numerical model predicted that the maximal propulsion from a 10 mm long tail can produce a velocity of 7.9 mm/s force of 5.5 mN when placed in a 3T static magnetic field. A validation study with a single coil demonstrated that the theoretical and numerical model predicts well the proposed swimming mechanism and it is useful for the fabrication of swimming tails.

Prostate cancer biopsy is a routine medical procedure, yet conventional techniques suffer from low sensitivity attributed to suboptimal image guidance and needle placement. Targeting small lesions and foci (5 mm in diameter) is particularly prone to errors. We developed an integrated system to perform robot-assisted transperineal needle insertions into the prostate, under Magnetic Resonance Imaging (MRI) guidance. The system provides arbitrary needle trajectories and allows for simultaneous surveillance and correction of the needle path, based on intra-operative MRI. System functionality and data transfer and processing tests were conducted. Five lesions embedded in the gel phantom were targeted successfully, while communication delays (due to higher image frame rates) had no adverse affect on robot-software communication. The system was sufficiently resistant to high network loads and performed with an acceptable transfer rate.

Searching for optimal needle insertion path by intraoperative magnetic resonance imaging (MRI) is complex and time-consuming task in MR-guided microwave thermotherapy of liver tumor. This paper reports the semi-active needle-guiding robot for MR-guided therapy by which a surgeon can freely selects needle insertion path while maintaining the remote center of motion at the pre-defined tumor site. The robot consists of three-degree-of-freedom active XYZ base stage with ultrasonic motors and passive needle holder with unconstrained two-degree-of-freedom rotation measured by optical fiber sensor with aluminum die cast. Once the target point on the tumor is defined in volumetric MR images, the base stage keeps the remote-center-of-motion at the target point, while physician can interactively selects the orientation of the needle path with continuous single slice MR imaging. Experiments to test the accuracy of remote-center-of-motion indicated that the robot can keep the needle tip with an average error of 0.7 ∼ 0.3 mm in the compatibility test showed the robot can be safely used in MR axial plane, and 1.0-0.4 mm in the sagittal plane. Unlike related studies published elsewhere where the MR compatible robot autonomously brings the tools to predefined location, the proposed approach is fit to use in microwave thermotherapy of liver cancer.

Transurethral resection of the prostate (TUR-P) is a common treatment for benign prostatic hyperplasia (BPH). However, the damage to the mucous membrane of the urethra leads to the complications. This paper reports a tubular organ resection manipulator for transurethral resection of the prostate which can minimize damage to the mucous membrane of the urethra using a prostate displacement mechanism and a continuous perfusion-resection mechanism. The manipulator has an arm, a cutter and a drill at the endeffector, and has 4 degrees-of-freedom: bending the arm, translating the cutter, rotating the drill and rotating the endeffector. The arm displaces the prostate, and the cutter is inserted linearly into the prostate and removes enlarged tissue by drilling. Combination of the arm and cutter enables the manipulator to remove sufficient volume of enlarged prostate through small incision on the urethra, thus minimizing the damage to the urethra. After finishing one plane cutting, the manipulator rotates its body and removes another part of the prostate gland. In performance experiments, each mechanism (bending motion, insertion, and body rotation) had high repeatability within 1.0 degree and within 0.1 mm. In phantom study, the manipulator could displace gelatin model accurately with sufficient power, and could reach and remove wide range of sample tissue (589.2 mm/sup 2/ in one procedure). These results showed that the manipulator can displace the prostate and remove sufficient volume of the prostate tissue through a small incision on the urethra.

This paper describes an autostereoscopic image overlay technique that is integrated into a surgical navigation system to superimpose a real three-dimensional (3-D) image onto the patient via a half-silvered mirror. The images are created by employing a modified version of integral videography (IV), which is an animated extension of integral photography. IV records and reproduces 3-D images using a microconvex lens array and flat display; it can display geometrically accurate 3-D autostereoscopic images and reproduce motion parallax without the need for special devices. The use of semitransparent display devices makes it appear that the 3-D image is inside the patient's body. This is the first report of applying an autostereoscopic display with an image overlay system in surgical navigation. Experiments demonstrated that the fast IV rendering technique and patient-image registration method produce an average registration accuracy of 1.13 mm. Experiments using a target in phantom agar showed that the system can guide a needle toward a target with an average error of 2.6 mm. Improvement in the quality of the IV display will make this system practical and its use will increase surgical accuracy and reduce invasiveness.

This paper proposes a new endoscopic hand-held forceps manipulator for endoscopic surgery using two bending mechanisms by multi-slider linkage mechanisms to achieve high mechanical performance and applicability. A bending mechanism consisted of three outer frames, two rotating joints and two sliding linkages for drive and restraint. Two pin-joints could rotate /spl plusmn/45 degrees respectively, enabling rotation of /spl plusmn/90 degrees. The rotation of the joint was available by pulling/pushing the adjacent element by sliding linkage in order. We connected two bending mechanisms, one was for the horizontal plane bending and the other was for the vertical plane bending, enabling 2-DOFs independent motions between -90 degrees and +90 degrees. The 2-DOFs bending mechanism and 1-DOF forceps mechanism were driven by three brushless DC-servomotors. A personal computer-based control unit determined displacement of sliding two linkages and of pulling one wire by the target angle of each DOF mechanism. We examined the actual angle of 2-DOFs bending mechanism, obtaining repeatability of /spl plusmn/0.87 degrees in the horizontal plane bending and /spl plusmn/0.91 degrees in the vertical plane bending. In vivo experiment, this manipulator performed endoscopic surgical tasks under pneumoperitoneum. In conclusion, we were sure of a usefulness of multi-slider linkage mechanism for the new handheld forceps manipulator for clinical application, which showed high repeatability of less 1.0 mm and large workspace with sufficient holding power of 0.55 kgf.

A novel device is described for efficiently harvesting bone marrow in bone marrow transplantation that uses a newly developed passive flexible drilling unit and suction mechanism. The device reduces the invasiveness of bone marrow harvesting by collecting stem cells from the iliac bone with minimal punctures and by reducing the operation time and the contamination by T-cells. The device is inserted into the medullary space from the iliac crest and aspirates the bone marrow while an end mill on the tip of the drilling unit drills through the cancellous bone to create a curved path. In vitro and in vivo pig studies showed that the device can be inserted into the medullary space of the pig iliac bone, 131 /spl times/ 32.1 mm/min, and used to harvest about six times as much bone marrow per puncture as the conventional aspiration method. They also showed that the device can generate higher and longer negative pressure (-76.9 kPa for 5.96 s) than the aspiration method (-41.8 kPa for 4.97 s). The device, when applied in clinical study, will reduce invasiveness by harvesting denser graft from a wider area of the iliac bone compared to the conventional aspiration method, although minimal puncturing is required.

A magnetic resonance (MR) compatible surgical assistance robot system, designed to aid minimally invasive surgical techniques, such as positioning and directing a catheter or a laser pointer, has been built and is under preclinical evaluation. Two specific issues arise in the MR environment: (i) the reduced space in which to place the robot; and (ii) the MR compatibility. The main mechanical body is located above the head of the surgeon, with two rigid, hanging arms that reach into the workspace. This novel configuration contributes to a small occupancy in the workspace and to the MR compatibility. The robot is also carefully designed for safety and sterilization issues. Details of the kinematics and the design of the robot are given, and the MR compatibility is examined. This shows that the robot has no adverse effect on the imaging, even when it is in motion.