EFFECTS OF TIP GEOMETRY OF SURGICAL NEEDLES: AN ASSESSMENT OF FORCE AND DEFLECTION

Abstract: Precise placement and steering of surgical needles is very important for many medical diagnostic and therapeutic procedures. But accurate steering and placement of needles in soft tissue is challenging because of a variety of reasons. In this study we focused on the effects of tip geometry (bevel tip, diamond tip, and conical tip) of brachytherapy needles while inserted in soft material phantoms. We have validated our hypothesis that rotation of needle can reduce deflection significantly

Feasibility study on a robot-assisted procedure for tumor localization using needle-rotation force signals

Accurate tumor localization is critical to early-stage cancer diagnosis and therapy. The recent force-guided technique allows to determine the depth of a suspicious tumor on the insertion path, while the spatial localization is still a great challenge. In this paper, a novel force-guided procedure was proposed to identify spatial tumor location using force signals during needle rotation. When there is a harder tumorous tissue around the needle rotation, an abnormal force signal will point to the location of the suspicious tissue. Finite element simulation and phantom experiment were conducted to test the feasibility of the procedure for the tumor localization. The simulation results showed that the harder tumorous tissue made a significant difference on the stress and deformation distributions for the surroundings, changing the needle-rotation force signals when the needle rotated towards the harder tissue. The experimental results indicated that the direction of the tumor location can be identified by the rotation-needle force signals. The intersection point of the two identified directions, derived from force signals of twice needle rotations, determined the tumor location ultimately. Also, parametric sensitivity tests were performed to examine the effective distance of the tumor location centre and the needle insertion point for the tumor localization. This procedure is expected to be used in robot-assisted system for cancer biopsy and brachytherapy

Precision grid and hand motion for accurate needle insertion in brachytherapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98741/1/MPH004749.pd

Penetration force measurements in the central nervous system with silicon electrodes

One of the major challenges in neural engineering is the tissue damage that occurs during insertion of microelectrodes into the central nervous system. The damage occurs as a result of the dimpling effect that is due to the insertion force. A method which can reduce the penetration force can also reduce dimpling and the resulting tissue damage. There are two objectives in this thesis. One is to measure the penetration force with Michigan electrodes, which are silicon based electrodes. The second is to reduce the penetration force by using mechanical vibrations. First, the penetration force was measured in the rat brain. To measure the penetration force, the microelectrode was connected to a load transducer. Because dura is a tough membrane to penetrate, it is usually removed during surgery in experimental animals. The dura mater was not removed in these experiments in order to keep the intactness of the cortex. The microelectrode was pulsed at a rate of 5 Hz using a piezoelectric crystal and a pulse generator. The results show that the vibration technique is successful in reducing the penetration force by 25%. In this study, we have concentrated only on reducing the penetration force in order to reduce dimpling. To our best knowledge no work has been yet reported on the use of vibrations for reducing electrode penetration force. Chronic experiments will have to be conducted to investigate if the vibrations alone cause any tissue damage

Haptics in Robot-Assisted Surgery: Challenges and Benefits

Robotic surgery is transforming the current surgical practice, not only by improving the conventional surgical methods but also by introducing innovative robot-enhanced approaches that broaden the capabilities of clinicians. Being mainly of man-machine collaborative type, surgical robots are seen as media that transfer pre- and intra-operative information to the operator and reproduce his/her motion, with appropriate filtering, scaling, or limitation, to physically interact with the patient. The field, however, is far from maturity and, more critically, is still a subject of controversy in medical communities. Limited or absent haptic feedback is reputed to be among reasons that impede further spread of surgical robots. In this paper objectives and challenges of deploying haptic technologies in surgical robotics is discussed and a systematic review is performed on works that have studied the effects of providing haptic information to the users in major branches of robotic surgery. It has been tried to encompass both classical works and the state of the art approaches, aiming at delivering a comprehensive and balanced survey both for researchers starting their work in this field and for the experts

Robotics-Assisted Needle Steering for Percutaneous Interventions: Modeling and Experiments

Needle insertion and guidance plays an important role in medical procedures such as brachytherapy and biopsy. Flexible needles have the potential to facilitate precise targeting and avoid collisions during medical interventions while reducing trauma to the patient and post-puncture issues. Nevertheless, error introduced during guidance degrades the effectiveness of the planned therapy or diagnosis. Although steering using flexible bevel-tip needles provides great mobility and dexterity, a major barrier is the complexity of needle-tissue interaction that does not lend itself to intuitive control. To overcome this problem, a robotic system can be employed to perform trajectory planning and tracking by manipulation of the needle base. This research project focuses on a control-theoretic approach and draws on the rich literature from control and systems theory to model needle-tissue interaction and needle flexion and then design a robotics-based strategy for needle insertion/steering. The resulting solutions will directly benefit a wide range of needle-based interventions. The outcome of this computer-assisted approach will not only enable us to perform efficient preoperative trajectory planning, but will also provide more insight into needle-tissue interaction that will be helpful in developing advanced intraoperative algorithms for needle steering. Experimental validation of the proposed methodologies was carried out on a state of-the-art 5-DOF robotic system designed and constructed in-house primarily for prostate brachytherapy. The system is equipped with a Nano43 6-DOF force/torque sensor (ATI Industrial Automation) to measure forces and torques acting on the needle shaft. In our setup, an Aurora electromagnetic tracker (Northern Digital Inc.) is the sensing device used for measuring needle deflection. A multi-threaded application for control, sensor readings, data logging and communication over the ethernet was developed using Microsoft Visual C 2005, MATLAB 2007 and the QuaRC Toolbox (Quanser Inc.). Various artificial phantoms were developed so as to create a realistic medium in terms of elasticity and insertion force ranges; however, they simulated a uniform environment without exhibiting complexities of organic tissues. Experiments were also conducted on beef liver and fresh chicken breast, beef, and ham, to investigate the behavior of a variety biological tissues

下腹部を対象とした極細針によるCTガイド下高正確度穿刺プランニング

早大学位記番号:新8149早稲田大

Design and validation of a device to measure the cutting edge profile of osteotomes

The cutting capacity of a cutting instrument is normally defined as its sharpness,\ud which defines the ability of the cutting edge to cut the target material. Many\ud factors therefore affect the ability of a blade to cut, including the target material,\ud the manufacturing process, and the cutting forces associated with cutting\ud technique employed (Kalder S., 1997).\ud In this study of techniques for measurement of the cutting edge profile various\ud methods were used to measure blade profiles and found that no one method of\ud measurement was capable of quantifying all the geometric parameters of the\ud cutting edge of the blade.\ud SUB3 (Sharpness of Unserrated Blades for Biomaterials and Biocomposites) is\ud a research project focusing on the specification of sharpness measurement for\ud surgical blades. A component of the work of the SUB3\ud project is the design and build of a prototype device for blade profile\ud measurement. This project contributes a device capable of measuring the\ud profile and wedge angle of the cutting flanks of a surgical osteotome.\ud The aim of this thesis is to investigate the measurement of sharpness with\ud particular relevance to non-contact measurement of the geometric parameters\ud of the surfaces of the cutting instrument.\ud All relevant current methods of profile measurement were investigated to\ud establish a suitable method for the measurement of the geometric properties of\ud a surgical osteotome using legacy technology, and also to establish if it could\ud be developed using existing components of measurement systems. If the\ud technology does not exist it is proposed to design and build a working prototype\ud non-contact profile measurement device capable of measuring the wedge angle\ud of a surgical osteotome

A Novel Flexible and Steerable Probe for Minimally Invasive Soft Tissue Intervention

Current trends in surgical intervention favour a minimally invasive (MI) approach, in which complex procedures are performed through increasingly small incisions. Specifically, in neurosurgery, there is a need for minimally invasive keyhole access, which conflicts with the lack of maneuverability of conventional rigid instruments. In an attempt to address this fundamental shortcoming, this thesis describes the concept design, implementation and experimental validation of a novel flexible and steerable probe, named “STING” (Soft Tissue Intervention and Neurosurgical Guide), which is able to steer along curvilinear trajectories within a compliant medium. The underlying mechanism of motion of the flexible probe, based on the reciprocal movement of interlocked probe segments, is biologically inspired and was designed around the unique features of the ovipositor of certain parasitic wasps. Such insects are able to lay eggs by penetrating different kinds of “host” (e.g. wood, larva) with a very thin and flexible multi-part channel, thanks to a micro-toothed surface topography, coupled with a reciprocating “push and pull” motion of each segment. This thesis starts by exploring these foundations, where the “microtexturing” of the surface of a rigid probe prototype is shown to facilitate probe insertion into soft tissue (porcine brain), while gaining tissue purchase when the probe is tensioned outwards. Based on these findings, forward motion into soft tissue via a reciprocating mechanism is then demonstrated through a focused set of experimental trials in gelatine and agar gel. A flexible probe prototype (10 mm diameter), composed of four interconnected segments, is then presented and shown to be able to steer in a brain-like material along multiple curvilinear trajectories on a plane. The geometry and certain key features of the probe are optimised through finite element models, and a suitable actuation strategy is proposed, where the approach vector of the tip is found to be a function of the offset between interlocked segments. This concept of a “programmable bevel”, which enables the steering angle to be chosen with virtually infinite resolution, represents a world-first in percutaneous soft tissue surgery. The thesis concludes with a description of the integration and validation of a fully functional prototype within a larger neurosurgical robotic suite (EU FP7 ROBOCAST), which is followed by a summary of the corresponding implications for future work