Real-time active constraint generation and enforcement for surgical tools using 3D detection and localisation network.

Introduction: Collaborative robots, designed to work alongside humans for manipulating end-effectors, greatly benefit from the implementation of active constraints. This process comprises the definition of a boundary, followed by the enforcement of some control algorithm when the robot tooltip interacts with the generated boundary. Contact with the constraint boundary is communicated to the human operator through various potential forms of feedback. In fields like surgical robotics, where patient safety is paramount, implementing active constraints can prevent the robot from interacting with portions of the patient anatomy that shouldn't be operated on. Despite improvements in orthopaedic surgical robots, however, there exists a gap between bulky systems with haptic feedback capabilities and miniaturised systems that only allow for boundary control, where interaction with the active constraint boundary interrupts robot functions. Generally, active constraint generation relies on optical tracking systems and preoperative imaging techniques. Methods: This paper presents a refined version of the Signature Robot, a three degrees-of-freedom, hands-on collaborative system for orthopaedic surgery. Additionally, it presents a method for generating and enforcing active constraints "on-the-fly" using our previously introduced monocular, RGB, camera-based network, SimPS-Net. The network was deployed in real-time for the purpose of boundary definition. This boundary was subsequently used for constraint enforcement testing. The robot was utilised to test two different active constraints: a safe region and a restricted region. Results: The network success rate, defined as the ratio of correct over total object localisation results, was calculated to be 54.7% ± 5.2%. In the safe region case, haptic feedback resisted tooltip manipulation beyond the active constraint boundary, with a mean distance from the boundary of 2.70 mm ± 0.37 mm and a mean exit duration of 0.76 s ± 0.11 s. For the restricted-zone constraint, the operator was successfully prevented from penetrating the boundary in 100% of attempts. Discussion: This paper showcases the viability of the proposed robotic platform and presents promising results of a versatile constraint generation and enforcement pipeline.

A New Venous Entry Detection Method Based on Electrical Bio-impedance Sensing.

Peripheral intravenous catheterization (PIVC) is frequently required for various medical treatments. Over 1 billion PIVC operations are performed per year in the United States alone. However, this operation is characterized by a very low success rate, especially amongst pediatric patients. Statistics show that only 53% of first PIVC attempts are successful in pediatric patients. Since their veins are small and readily rupture, multiple attempts are commonly required before successfully inserting the catheter into the vein. This article presents and evaluates a novel venous entry detection method based on measuring the electrical bio-impedance of the contacting tissue at the tip of a concentric electrode needle (CEN). This detection method is then implemented in the design of a clinical device called smart venous entry indicator (SVEI), which lights up a LED to indicate the venous entry when the measured value is within the range of blood. To verify this detection method, two experiments are conducted. In the first experiment, we measured the bio-impedance during the insertion of a CEN into a rat's tail vein with different excitation frequencies. Then three classifiers are tested to discriminate blood from surrounding tissues. The experimental results indicate that with 100 kHz excitation frequency the blood bio-impedance can be identified with accuracy nearly 100%, demonstrating the feasibility and reliability of the proposed method for venous entry detection. The second experiment aims to assess the impact of SVEI on PIVC performance. Ten naive subjects were invited to catheterize a realistic baby arm phantom. The subjects are equally divided into two groups, where one group does PIVC with SVEI and the other group uses an ordinary IV catheter. The results show that subjects using SVEI can achieve much higher success rates (86%) than those performing PIVC in a conventional way (12%). Also, all subjects assisted by SVEI succeeded in their first trials while no one succeed in their first attempt using the conventional unassisted system. These results demonstrate the proposed detection method has great potential to improve pediatric PIVC performance, especially for non-expert clinicians. This supports further investment towards clinical validation of the technology.

A hand-held robotic device for peripheral intravenous catheterization.

Intravenous catheterization is frequently required for numerous medical treatments. However, this process is characterized by a high failure rate, especially when performed on difficult patients such as newborns and infants. Very young patients have small veins, and that increases the chances of accidentally puncturing the catheterization needle directly through them. In this article, we present the design, development and experimental evaluation of a novel hand-held robotic device for improving the process of peripheral intravenous catheterization by facilitating the needle insertion procedure. To our knowledge, this design is the first hand-held robotic device for assisting in the catheterization insertion task. Compared to the other available technologies, it has several unique advantages such as being compact, low-cost and able to reliably detect venipuncture. The system is equipped with an electrical impedance sensor at the tip of the catheterization needle, which provides real-time measurements used to supervise and control the catheter insertion process. This allows the robotic system to precisely position the needle within the lumen of the target vein, leading to enhanced catheterization success rate. Experiments conducted to evaluate the device demonstrated that it is also effective to deskill the task. Naïve subjects achieved an average catheterization success rate of 88% on a 1.5 mm phantom vessel with the robotic device versus 12% with the traditional unassisted system. The results of this work prove the feasibility of a hand-held assistive robotic device for intravenous catheterization and show that such device has the potential to greatly improve the success rate of these difficult operations.

Modelling needle forces during insertion into soft tissue.

Robot-assisted needle-based surgeries are sought to improve many operations, from brain surgery to spine and urological procedures. Force feedback from a needle can provide important guidance during needle insertion. This paper presents a new modelling method of needle force during insertion into soft tissue based on finite element simulation. This is achieved by analysing the results of a series of needle inserting experiments with different insertion velocities. The forces acting on the needle are then modelled based on the experimental results. A simulation is implemented to verify the designed model.

Microtextured surfaces for deep-brain stimulation electrodes: a biologically inspired design to reduce lead migration.

OBJECTIVE: Hardware-related complications of deep brain stimulation (DBS) surgery have been reported with adverse effects in postoperative electrode migration. We report that the addition of microtextured features to the surface of a DBS-like probe can minimize the extent of electrode migration in ex vivo porcine brain. METHODS: A DBS lead and microtextured strips, mounted with a fiberoptic displacement sensor, were embedded 15-mm deep inside a cadaveric porcine brain through holes on the skull. The local displacement of brain tissue surrounding each strip was detected along the direction of insertion by the optical sensor while the porcine head simulated brain shift during rotation between supine and upright postures. RESULTS: The triangular toothed strip with protruding height of 250 µm enabled a better grip of the surrounding brain tissue than standard DBS lead, minimizing local brain displacement to 77 µm versus 326 µm respectively, when the porcine head was shifted from the supine to the upright position as the result of gravity. In addition, brain tissue damage resulting from the removal of toothed strips exhibited less-extensive tissue disruption, attributable to the microtextured surface. CONCLUSIONS: These preliminary results show that microtextured strips embedded into cadaveric porcine brain produce an anchoring effect on local tissue during brain shift, suggesting a way to reduce DBS lead migration without additional tissue damage beyond the strip geometry.

Robotic system for transrectal biopsy of the prostate: real-time guidance under MRI.

In this paper, to harness the possibility of real-time guidance of MRI, a robotic system has been developed to perform transrectal prostate biopsy inside a 1.5-T closed bore scanner. A specially developed MR pulse sequence is capable of tracking the needle location in real time while dynamically updating the scan planes to always include the needle and target.

The case for MR-compatible robotics: a review of the state of the art.

BACKGROUND: The numerous imaging capabilities of magnetic resonance imaging (MRI) coupled with its lack of ionizing radiation has made it a desirable modality for real-time guidance of interventional procedures. The combination of these abilities with the advantages granted by robotic systems to perform accurate and precise positioning of tools has driven the recent development of MR-compatible interventional and assistive devices. METHODS: The challenges in this field are presented, including the selection of suitable materials, actuators and sensors in the intense magnetic fields of the MR environment. RESULTS: Only a small number of developed systems have made it to the clinical level (only two have become commercial ventures), showing that the field has not yet reached maturity. CONCLUSIONS: A brief overview of the current state of the art is given, along with a description of the main opportunities, possibilities and challenges that the future will bring to this exciting and promising field.