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Preview: The International Journal of Medical Robotics and Computer Assisted Surgery

The International Journal of Medical Robotics and Computer Assisted Surgery

Wiley Online Library : The International Journal of Medical Robotics and Computer Assisted Surgery

Published: 2018-02-01T00:00:00-05:00


Inter- and intra-operator reliability in patient-specific template positioning for total hip arthroplasty. A cadaver study


Background The implantation of the acetabular cup essentially determines the clinical outcome of total hip arthroplasty. To address this issue, the aim of this study was to build patient-specific instruments (PSIs) with various reference surfaces, followed by in vitro investigations to examine the inter- and intra-operator reliability as well as the overall precision of these patient-specific templates. Methods Seven human hemi-pelvis specimens were used for this study. After a CT scan, PSIs with different imprint heights were created. The overall precision of the templates and the inter- and intra-operator reliabilities were calculated. Results Strong differences in precision between the PSI designs could be observed. The desired orientation of the acetabular cup could be adjusted with a precision of up to 1.55°. Conclusion Based on our results, we believe that the application of the PSI-based acetabular cup positioning in total hip arthroplasty procedures can potentially increase the precision of cup placement.

Operator dynamics for stability condition in haptic and teleoperation system: A survey


Background Currently, haptic systems ignore the varying impedance of the human hand with its countless configurations and thus cannot recreate the complex haptic interactions. The literature does not reveal a comprehensive survey on the methods proposed and this study is an attempt to bridge this gap. Methods The paper includes an extensive review of human arm impedance modeling and control deployed to address inherent stability and transparency issues in haptic interaction and teleoperation systems. Results Detailed classification and comparative study of various contributions in human arm modeling are presented and summarized in tables and diagrams. Conclusion The main challenges in modeling human arm impedance for haptic robotic applications are identified. The possible future research directions are outlined based on the gaps identified in the survey.

Using optical tracking for kinematic testing of medical robots


Background In image-guided robotic interventions, an error component is related to the positioning error of the manipulator. Therefore, measuring the kinematic error is required during robot development. However, no specialized measurement device exists for this task. This study explores the possibility of using optical tracking for robot measurement. Methods A CNC machine is used to position an optical marker, generating a gold standard reference. Repeated position measurements are acquired with an NDI Polaris Hybrid® optical tracker at each static location, and averaged. These measurements are compared to the reference set. Results Averaging repeated static position measurements improves precision (200–500 samples). Measurement accuracy ranges between 44 μm and 137 μm in close proximity of the tracker. Conclusions Repeated static position measurements in the near field of view enable the optical tracker to outperform its general-purpose accuracy specification. Optical tracking may be used to test robot kinematics with a high degree of accuracy.

A novel planning solution for semi-autonomous aspiration of Baker's cysts


Background A Baker's cyst is a pathological structure located near a kneepit, which causes discomfort and reduces mobility of the knee. It is commonly treated with aspiration, which often requires MRI scanning and US guidance. The aim of this study was to propose a novel planning solution for semi-autonomous aspiration of the Baker's cyst using only MRI imaging. Methods The proposed method requires minimal user input and offers automatic cyst segmentation with collision-free path planning for the assumed robotic structure with four degrees of freedom. Results The prepared software was tested on four image sets obtained from patients eligible for cyst aspiration. It was possible to accurately segment the cyst in the considered cases. The collision-free path planning method was investigated in numerical scenarios. Conclusions The simulations verified the proposed software solution. Future work will be devoted to experimental verification of the path planning procedure.

Robot-guided stereoelectroencephalography without a computed tomography scan for referencing: Analysis of accuracy


Objective Recent studies with robot-guided stereotaxy use computed tomography (CT) scans for referencing. We will provide evidence that using preoperative MRI datasets referenced with a laser scan of the patient's face is sufficient for sEEG implantation. Methods In total, 40 sEEG electrodes were implanted in five patients by the robotic surgical assistant (ROSA). The postoperative CT scan for identifying electrode positions was fused with the preoperative MRI-based planning data. The accuracy was determined by the target point error (TPE) and the entry point error (EPE), applying the Euclidean distance. Results The mean TPE amounted to 2.96 mm, the mean EPE to 2.53 mm. The accuracy was improved in 1.5 T MRI: the mean TPE amounted to 1.72 mm, the EPE to 0.97 mm. No complications, haemorrhages, infections, etc., were observed. Conclusions Robot-guided sEEG based on 3 T MRI reduces radiation exposure for the patient and can still be performed safely.

Endoscopic navigation system with extended field of view using augmented reality technology


Background While endoscopic skull base surgery (ESBS) has emerged as an alternative surgical option, the limited field of view of the endoscope may lead to the surgeon's fatigue and discomfort. Methods The developed navigation system includes extended augmented reality (AR), which can provide an extended viewport to a conventional endoscopic view by overlaying 3D anatomical models generated from preoperative medical images onto endoscope images. To enhance the accuracy of the developed system, we adopted state-of-the-art endoscopic calibration and tracking techniques based on an optical tracking system. Results The mean spatial errors of AR was ~1 mm, which falls in the acceptable range of accuracy for ESBS. For the simulated surgical tasks with the developed system, the number and duration of error events were decreased. Conclusions The results show that the human subject can perform the task more precisely and safely with the developed AR-based navigation system than with the conventional endoscopic system.

Visual and tactile feedback for a direct-manipulating tactile sensor in laparoscopic palpation


Background A surgeon's tactile sense can contribute to intraoperative tumor detection, but it is limited by laparoscopic surgery. Methods We have developed a simple and biocompatible tactile sensor. This study aimed to design and evaluate visual and tactile feedback from the sensor for laparoscopic tumor detection. A line graph was offered through a monitor as the visual feedback. A normal force was presented to the user's foot as the tactile feedback. Twelve novices conducted a task of detecting a phantom tumor under 4 conditions (no feedback, visual feedback, tactile feedback and a combination of both types of feedback). Results The visual feedback was significantly more effective in detection than no feedback. Moreover, both visual and tactile feedback led to safer manipulation with significantly smaller load and lower scanning speed, respectively. Conclusions The results suggest that visual and tactile feedback can be useful for laparoscopic palpation; however, their effects depend on the means in which they are presented.

Camera-augmented mobile C-arm (CamC): A feasibility study of augmented reality imaging in the operating room


Background In orthopaedic trauma surgery, image-guided procedures are mostly based on fluoroscopy. The reduction of radiation exposure is an important goal. The purpose of this work was to investigate the impact of a camera-augmented mobile C-arm (CamC) on radiation exposure and the surgical workflow during a first clinical trial. Methods Applying a workflow-oriented approach, 10 general workflow steps were defined to compare the CamC to traditional C-arms. The surgeries included were arbitrarily identified and assigned to the study. The evaluation criteria were radiation exposure and operation time for each workflow step and the entire surgery. The evaluation protocol was designed and conducted in a single-centre study. Results The radiation exposure was remarkably reduced by 18 X-ray shots 46% using the CamC while keeping similar surgery times. Conclusions The intuitiveness of the system, its easy integration into the surgical workflow, and its great potential to reduce radiation have been demonstrated.

Issue Information


No abstract is available for this article.

Development of a novel robotic platform with controllable stiffness manipulation arms for laparoendoscopic single-site surgery (LESS)


Background For current LESS robotic systems, the trade-off between dexterity and payload capability is always present. This paper presents a novel LESS robotic platform equipped with controllable stiffness manipulation arms. Methods Each manipulation arm with an articulated section and a controllable stiffness continuum section (CSCS) can be switched between a 7-DoF compliant status and 5-DoF rigid status according to the operation requirement. Screw theory and product exponential formula are used to quantify the kinematic performance. Results The stiffness of the manipulation arm promotes 3.03 to 4.12 times from compliant to rigid CSCS with maximum payload of 10 N in rigid status. The shortest rigid/compliant switching time is 5 s. The precision of a tracking test and an ex vivo procedure verified the accuracy and effectiveness of the controllable stiffness manipulation arms. Conclusions This robot could potentially improve the surgical performance and further expand robotic LESS procedures.

Intraocular robotic interventional surgical system (IRISS): Mechanical design, evaluation, and master–slave manipulation


Background: Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed. Methods: An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography (OCT) system. Results: The IRISS can simultaneously manipulate multiple surgical instruments, change between mounted tools using an onboard tool-change mechanism, and visualize the otherwise invisible RCMs to facilitate alignment of the RCM to the surgical incision. The accuracy of positioning the tool tip was measured to be 0.205±0.003 mm. The IRISS was evaluated by trained surgeons in a remote surgical theatre using post-mortem pig eyes and shown to be effective in completing many key steps in a variety of intraocular surgical procedures as well as being capable of performing an entire cataract extraction from start to finish. Conclusions: The IRISS represents a necessary step towards fully automated intraocular surgery and demonstrated accurate and precise master-slave manipulation for cataract removal and—through visual feedback—retinal vein cannulation.

Motion control skill assessment based on kinematic analysis of robotic end-effector movements


Background The performance of robotic end-effector movements can reflect the user's operation skill difference in robot-assisted minimally invasive surgery. This study quantified the trade-off of speed–accuracy–stability by kinematic analysis of robotic end-effector movements to assess the motion control skill of users with different levels of experience. Methods Using ‘MicroHand S’ system, 10 experts, 10 residents and 10 novices performed single-hand test and bimanual coordination test. Eight metrics based on the movements of robotic end-effectors were applied to evaluate the users' performance. Results In the single-hand test, experts outperformed other groups except for movement speed; in the bimanual coordination test, experts also performed better except for movement time and movement speed. No statistically significant difference in performance was found between residents and novices. Conclusions The kinematic differences obtained from the movements of robotic end-effectors can be applied to assess the motion control skill of users with different skill levels.

Manipulator-driven selection of semi-active MR-visible markers


Background A method for the identification of semi-active fiducial magnetic resonance (MR) markers is presented based on selectively optically tuning and detuning them. Methods Four inductively coupled solenoid coils with photoresistors were connected to light sources. A microcontroller timed the optical tuning/detuning of coils and image collection. The markers were tested on an MR manipulator linking the microcontroller to the manipulator control to visibly select the marker subset according to the actuated joint. Results In closed-loop control, the average and maximum were 0.76° ± 0.41° and 1.18° errors for a rotational joint, and 0.87 mm ± 0.26 mm and 1.13 mm for the prismatic joint. Conclusions This technique is suitable for MR-compatible actuated devices that use semi-active MR-compatible markers.

EyeSLAM: Real-time simultaneous localization and mapping of retinal vessels during intraocular microsurgery


Background Fast and accurate mapping and localization of the retinal vasculature is critical to increasing the effectiveness and clinical utility of robot-assisted intraocular microsurgery such as laser photocoagulation and retinal vessel cannulation. Methods The proposed EyeSLAM algorithm delivers 30 Hz real-time simultaneous localization and mapping of the human retina and vasculature during intraocular surgery, combining fast vessel detection with 2D scan-matching techniques to build and localize a probabilistic map of the vasculature. Results In the harsh imaging environment of retinal surgery with high magnification, quick shaky motions, textureless retina background, variable lighting and tool occlusion, EyeSLAM can map 75% of the vessels within two seconds of initialization and localize the retina in real time with a root mean squared (RMS) error of under 5.0 pixels (translation) and 1° (rotation). Conclusions EyeSLAM robustly provides retinal maps and registration that enable intelligent surgical micromanipulators to aid surgeons in simulated retinal vessel tracing and photocoagulation tasks.

MRI-compatible breast/rib phantom for evaluating ultrasonic thermal exposures


Introduction The target of this study was the development of a magnetic resonance imaging (MRI) compatible breast phantom for focused ultrasound which includes plastic (ABS) ribs. The objective of the current study was the evaluation of a focused ultrasound procedure using the proposed phantom that eliminates rib heating. Material and Methods The proposed phantom was evaluated using two different focused ultrasound exposures. The surrounding breast tissue was mimicked using an agar–silica–evaporation milk gel (2% w/v – 2% w/v – 40% v/v). Results The attenuation of the ABS was similar to that of ribs. MR thermometry of focused ultrasound exposures were acquired using the breast/rib phantom. In one exposure focused ultrasound was applied with far-field targeting of the ribs. In the other exposure, the transducer was positioned laterally, thus avoiding exposure of the rib to focused ultrasound. Conclusions Due to growing interest in using MRI guided focused ultrasound (MRgFUS) for patients with breast cancer, the proposed breast/rib phantom can be utilized as a very useful tool for evaluating ultrasonic protocols.

Automated robot-assisted surgical skill evaluation: Predictive analytics approach


Background Surgical skill assessment has predominantly been a subjective task. Recently, technological advances such as robot-assisted surgery have created great opportunities for objective surgical evaluation. In this paper, we introduce a predictive framework for objective skill assessment based on movement trajectory data. Our aim is to build a classification framework to automatically evaluate the performance of surgeons with different levels of expertise. Methods Eight global movement features are extracted from movement trajectory data captured by a da Vinci robot for surgeons with two levels of expertise – novice and expert. Three classification methods – k-nearest neighbours, logistic regression and support vector machines – are applied. Results The result shows that the proposed framework can classify surgeons' expertise as novice or expert with an accuracy of 82.3% for knot tying and 89.9% for a suturing task. Conclusion This study demonstrates and evaluates the ability of machine learning methods to automatically classify expert and novice surgeons using global movement features.

Influence of surgical gloves on haptic perception thresholds


Background Impairment of haptic perception by surgical gloves could reduce requirements on haptic systems for surgery. While grip forces and manipulation capabilities were not impaired in previous studies, no data is available for perception thresholds. Methods Absolute and differential thresholds (20 dB above threshold) of 24 subjects were measured for frequencies of 25 and 250 Hz with a Ψ-method. Effects of wearing a surgical glove, moisture on the contact surface and subject's experience with gloves were incorporated in a full-factorial experimental design. Results Absolute thresholds of 12.8 dB and −29.6 dB (means for 25 and 250 Hz, respectively) and differential thresholds of −12.6 dB and −9.5 dB agree with previous studies. A relevant effect of the frequency on absolute thresholds was found. Comparisons of glove- and no-glove-conditions did not reveal a significant mean difference. Conclusions Wearing a single surgical glove does not affect absolute and differential haptic perception thresholds.

An automated skills assessment framework for laparoscopic training tasks


Background Various sensors and methods are used for evaluating trainees' skills in laparoscopic procedures. These methods are usually task-specific and involve high costs or advanced setups. Methods In this paper, we propose a novel manoeuver representation feature space (MRFS) constructed by tracking the vanishing points of the edges of the graspers on the video sequence frames, acquired by the standard box trainer camera. This study aims to provide task-agnostic classification of trainees in experts and novices using a single MRFS over two basic laparoscopic tasks. Results The system achieves an average of 96% correct classification ratio (CCR) when no information on the performed task is available and >98% CCR when the task is known, outperforming a recently proposed video-based technique by >13%. Conclusions Robustness, extensibility and accurate task-agnostic classification between novices and experts is achieved by utilizing advanced computer vision techniques and derived features from a novel MRFS.

Finite element analysis of customized implant in mandibular reconstruction after tumor resection with and without using customized surgical osteotomy guide


Objectives The aim of this work was to compare different 12 cases (3 patients * 4 cases = 12 cases) with varying gaps between implant and bone by analyzing the effect of these gaps on implant and screws using FEM. Methods In each patient's case 1 using CSOG and in case 2, 3, and 4 without using CSOG tumor cutting was done. Hence in each patient zero gaps at case 1 and overcutting at case 2, 3, and 4 have obtained at different locations. Results FEM results reveal that in each patient's case 4 (maximum gap) was more susceptible to loosening of the screws due to higher strains (37%) and implant failure due to higher stress (28%) concentration under the same loading conditions when compared with case 1 (zero gap). Conclusions The study reveals that mandibular reconstruction with implant placement using CSOG can significantly enhance the stability and safety of the implant.

A novel approach for intra-operative shape acquisition of the tibio-femoral joints using 3D laser scanning in computer assisted orthopaedic surgery


Background Image registration (IR) is an important process of developing a spatial relationship between pre-operative data and the physical patient in the operation theatre. Current IR techniques for Computer Assisted Orthopaedic Surgery (CAOS) are time consuming and costly. There is a need to automate and accelerate this process. Methods Bespoke quick, cost effective, contactless and automated 3D laser scanning techniques based on the DAVID Laserscanner method were designed. 10 cadaveric knee joints were intra-operatively laser scanned and were registered with the pre-operative MRI scans. The results are supported with a concurrent validity study. Results The average absolute errors between scan models were systematically less than 1 mm. Errors on femoral surfaces were higher than tibial surfaces (P<0.05). Additionally, scans acquired through the large exposure produced higher errors than the smaller exposure (P<0.05). Conclusion This study has provided proof of concept for a novel automated shape acquisition and registration technique for CAOS.

Improving the human–robot interface for telemanipulated robotic long bone fracture reduction: Joystick device vs. haptic manipulator


Objectives Intramedullary nailing is the treatment of choice for femoral shaft fractures. However, there are several problems associated with the technique, e.g. high radiation exposure and rotational malalignment. Experimental robotic assistance has been introduced to improve the quality of the reduction and to reduce the incidence of rotational malalignment. In the current study, we compare two devices for control of the fracture fragments during telemanipulated reduction. Methods Ten male and ten female subjects were asked to participate as examiners in this experiment. A computer program was developed to render and manipulate CT-based renderings of femur fracture bone fragments. The user could manipulate the fragments using either a simple joystick device or a haptic manipulator. Each examiner performed telemanipulated reduction of 10 virtual fracture models of varying difficulty with each device (five in a ‘training phase’ and five in a ‘testing phase’). Mixed models were used to test whether using the haptic device improved alignment accuracy and improved reduction times compared to using a joystick. Results Reduction accuracy was not significantly different between devices in either the training phase or the testing phase (P > 0.05). Reduction time was significantly higher for the Phantom device than for the Joystick in the training phase (P < 0.0001), but it was no different in the testing phase (P = 0.865). High spatial ability with electronics had a significant effect on the alignment of fracture reduction and time to reduction. Conclusions The Joystick and the Phantom devices resulted in similarly accurate reductions, with the Joystick having an easier learning curve. The Phantom device offered no advantage over the Joystick for fracture telemanipulation. Considering the high cost of the Phantom device and the lack of a demonstrable advantage over the Joystick, its use is not justified for implementation in a fracture telemanipulation workflow. The Joystick remains as a low-cost and effective device for developing 3D fracture telemanipulation techniques.

Comparison of algorithms for automated femur fracture reduction


Purpose We designed an experiment to determine the comparative effectiveness of computer algorithms for performing automated long bone fracture reduction. Methods Automated reduction of 10 3D fracture models was performed using two computer algorithms, random sample matching (RANSAM) and Z-buffering (Z-Buffer), and one of five options of post-processing: none; iterative closest point algorithm (ICP); ICP-X1; ICP-X2; and ICP-X3. We measured the final alignment between the two fragments for each algorithm and post-processing option. Results The RANSAM algorithm combined with postprocessing algorithm ICP-X1 or ICP-X3 resulted in the most accurate fracture reduction in the translational plane. No discernible difference was observed in the rotational plane. Automated reduction had more accurate translational displacement than telemanipulated manual reductions. Conclusion This study supports the use of the RANSAM algorithm for automated fracture reduction procedures. The use of ICP algorithms provides further optimization of the initial reduction.

A master manipulator with a remote-center-of-motion kinematic structure for a minimally invasive robotic surgical system


Background In robotic surgical systems, commercial master devices have limitations owing to insufficient workspace and lack of intuitiveness. To overcome these limitations, a remote-center-of-motion (RCM) master manipulator was proposed. Methods The feasibility of the proposed RCM structure was evaluated through kinematic analysis using a conventional serial structure. Two performance comparison experiments (peg transfer task and objective transfer task) were conducted for the developed master and Phantom Omni. Results The kinematic analysis results showed that compared with the serial structure, the proposed RCM structure has better performance in terms of design efficiency (19%) and workspace quality (59.08%). Further, in comparison with Phantom Omni, the developed master significantly increased task efficiency and significantly decreased workload in both experiments. Conclusions The comparatively better performance in terms of intuitiveness, design efficiency, and operability of the proposed master for a robotic system for minimally invasive surgery was confirmed through kinematic and experimental analysis.

Modeling the convergence accommodation of stereo vision for binocular endoscopy


Background The stereo laparoscope is an important tool for achieving depth perception in robot-assisted minimally invasive surgery (MIS). Methods A dynamic convergence accommodation algorithm is proposed to improve the viewing experience and achieve accurate depth perception. Based on the principle of the human vision system, a positional kinematic model of the binocular view system is established. The imaging plane pair is rectified to ensure that the two rectified virtual optical axes intersect at the fixation target to provide immersive depth perception. Results Stereo disparity was simulated with the roll and pitch movements of the binocular system. The chessboard test and the endoscopic peg transfer task were performed, and the results demonstrated the improved disparity distribution and robustness of the proposed convergence accommodation method with respect to the position of the fixation target. Conclusions This method offers a new solution for effective depth perception with the stereo laparoscopes used in robot-assisted MIS.

Robotic-assisted versus open radical cystectomy in bladder cancer: A meta-analysis of four randomized controlled trails


Background Robot-assisted radical cystectomy (RARC) is increasing annually for treatment of bladder cancer. The objective of this meta-analysis was to compare the safety and efficacy of RARC and open radical cystectomy (ORC) for bladder cancer. Methods Our meta-analysis searches were conducted using PubMed, Web of Science, and Cochrane Library databases to identify randomized controlled trials (RCT) assessing the two techniques. Results Four RCT studies were identified, including 239 cases. Our studies indicated that RARC was associated with longer operative time (WMD: 69.69, 95% CI:17.25 to122.12; P= 0.009), lower estimated blood loss (WMD: –299.83, 95% CI:–414.66to −184.99; P<0.00001). The two groups had no significant difference in overall perioperative complications, length of hospital stay, lymph node yield and positive surgical margins. Conclusions RARC is mini-invasive alternative to ORC for bladder cancer. The advantage of RARC was reduced estimated blood loss. More studies are needed to compare the two techniques.

Development of a physical shoulder simulator for the training of basic arthroscopic skills


Background Orthopaedic training programs are incorporating arthroscopic simulations into their residency curricula. There is a need for a physical shoulder simulator that accommodates lateral decubitus and beach chair positions, has realistic anatomy, allows for an objective measure of performance and provides feedback to trainees. Methods A physical shoulder simulator was developed for training basic arthroscopic skills. Sensors were embedded in the simulator to provide a means to assess performance. Subjects of varying skill level were invited to use the simulator and their performance was objectively assessed. Results Novice subjects improved their performance after practice with the simulator. A survey completed by experts recognized the simulator as a valuable tool for training basic arthroscopic skills. Conclusions The physical shoulder simulator helps train novices in basic arthroscopic skills and provides objective measures of performance. By using the physical shoulder simulator, residents could improve their basic arthroscopic skills, resulting in improved patient safety.

Feasibility of infrared tracking of beating heart motion for robotic assisted beating heart surgery


Background Accurate tracking of the heart surface motion is a major requirement for robot assisted beating heart surgery. Method The feasibility of a stereo infrared tracking system for measuring the free beating heart motion was investigated by experiments on a heart motion simulator, as well as model surgery on a dog. Results Simulator experiments revealed a high tracking accuracy (81 μm root mean square error) when the capturing times were synchronized and the tracker pointed at the target from a 100 cm distance. The animal experiment revealed the applicability of the infrared tracker with passive markers in practical heart surgery conditions. Conclusion With the current technology, infrared tracking with passive markers might be the optimal solution for accurate, fast, and reliable tracking of heart motion during robot assisted beating heart surgery.

Real-time probe tracking using EM-optical sensor for MRI-guided cryoablation


Background A method of real-time, accurate probe tracking at the entrance of the MRI bore is developed, which, fused with pre-procedural MR images, will enable clinicians to perform cryoablation efficiently in a large workspace with image guidance. Methods Electromagnetic (EM) tracking coupled with optical tracking is used to track the probe. EM tracking is achieved with an MRI-safe EM sensor working under the scanner's magnetic field to compensate the line-of-sight issue of optical tracking. Unscented Kalman filter-based probe tracking is developed to smooth the EM sensor measurements when occlusion occurs and to improve the tracking accuracy by fusing the measurements of two sensors. Results Experiments with a spine phantom show that the mean targeting errors using the EM sensor alone and using the proposed method are 2.21 mm and 1.80 mm, respectively. Conclusion The proposed method achieves more accurate probe tracking than using an EM sensor alone at the MRI scanner entrance.

Semi-autonomous image-guided brain tumour resection using an integrated robotic system: A bench-top study


Background Complete brain tumour resection is an extremely critical factor for patients' survival rate and long-term quality of life. This paper introduces a prototype medical robotic system that aims to automatically detect and clean up brain tumour residues after the removal of tumour bulk through conventional surgery. Methods We focus on the development of an integrated surgical robotic system for image-guided robotic brain surgery. The Behavior Tree framework is explored to coordinate cross-platform medical subtasks. Results The integrated system was tested on a simulated laboratory platform. Results and performance indicate the feasibility of supervised semi-automation for residual brain tumour ablation in a simulated surgical cavity with sub-millimetre accuracy. The modularity in the control architecture allows straightforward integration of further medical devices. Conclusions This work presents a semi-automated laboratory setup, simulating an intraoperative robotic neurosurgical procedure with real-time endoscopic image guidance and provides a foundation for the future transition from engineering approaches to clinical application.

Performance metrics for guidance active constraints in surgical robotics


Active constraint (AC)/virtual fixture (VF) is among the most popular approaches towards the shared execution of subtasks by the surgeon and robotic systems. As more possibilities appear for the implementation of ACs in surgical scenarios, the need to introduce methods that guarantee a safe and intuitive user-interaction increases. The presence of the human in the loop adds a layer of interactivity and adaptability that renders the assessment of such methods non-trivial. In most works, guidance ACs have been evaluated mainly in terms of enhancement of accuracy and completion time with little regard for other aspects such as human factors, even though the continuous engagement of these methods can considerably degrade the user experience. This paper proposes a set of performance metrics and considerations that can help evaluate guidance ACs with reference to accuracy enhancement, force characteristics and subjective aspects. The use of these metrics is demonstrated through two sets of experiments on 12 surgeons and 6 inexperienced users.

A comparative analysis and guide to virtual reality robotic surgical simulators


Background Since the US Food and Drug Administration approved robotically assisted surgical devices for human surgery in 2000, the number of surgeries utilizing this innovative technology has risen. In 2015, approximately 650 000 robot-assisted procedures were performed worldwide. Surgeons must be properly trained to safely transition to using such innovative technology. Multiple virtual reality robotic simulators are now commercially available for educational and training purposes. There is a need for comparative evaluations of these simulators to aid users in selecting an appropriate device for their purposes. Methods We conducted a comparison of the design and capabilities of all dedicated simulators of the da Vinci robot – the da Vinci Skills Simulator (dVSS), dV-Trainer (dVT), Robotic Skills Simulators (RoSS) and the RobotiX Mentor. This paper provides the base specifications of the hardware and software, with an emphasis on the training capabilities of each system. Results Each simulator contains a large number of training exercises for skills development: dVSS n = 40, dVT n = 65, RoSS n = 52, RobotiX Mentor n = 31. All four offer 3D visual images but use different display technologies. The dVSS leverages the real robotic surgical console to provide visualization, hand controls and foot pedals. The dVT, RoSS and RobotiX Mentor created simulated versions of all of these control systems. Each includes systems management services that allow instructors to collect, export and analyze the scores of students using the simulators. Conclusions This study provides comparative information on the four simulators' functional capabilities. Each device offers unique advantages and capabilities for training robotic surgeons. Each has been the subject of validation experiments, which have been published in the literature. But those do not provide specific details on the capabilities of the simulators, which are necessary for an understanding sufficient to select the one best suited for an organization's needs. This article provides comparative information to assist with that type of selection.

Highly dexterous 2-module soft robot for intra-organ navigation in minimally invasive surgery


Background For some surgical interventions, like the Total Mesorectal Excision (TME), traditional laparoscopes lack the flexibility to safely maneuver and reach difficult surgical targets. This paper answers this need through designing, fabricating and modelling a highly dexterous 2-module soft robot for minimally invasive surgery (MIS). Methods A soft robotic approach is proposed that uses flexible fluidic actuators (FFAs) allowing highly dexterous and inherently safe navigation. Dexterity is provided by an optimized design of fluid chambers within the robot modules. Safe physical interaction is ensured by fabricating the entire structure by soft and compliant elastomers, resulting in a squeezable 2-module robot. An inner free lumen/chamber along the central axis serves as a guide of flexible endoscopic tools. A constant curvature based inverse kinematics model is also proposed, providing insight into the robot capabilities. Results Experimental tests in a surgical scenario using a cadaver model are reported, demonstrating the robot advantages over standard systems in a realistic MIS environment. Conclusion Simulations and experiments show the efficacy of the proposed soft robot.

System for CT-guided needle placement in the thorax and abdomen: A design for clinical acceptability, applicability and usability


Background: Various systems exist for CT-guided needle placement in the thorax and abdomen, but widespread adoption is lacking. The goal of this work is to develop a system for precise needle placement with a design focus on clinical acceptability, applicability and usability. Methods: A system was outlined incorporating a needle guide on a mechanism with a remote centre of motion, manually placeable around the patient at the desired entry point and lockable by push-button to the CT table. System and patient are scanned for system-to-CT registration and target specification. The needle guide is automatically aimed at the target, for manual needle insertion to specified depth. Results: A fully functional prototype was realized, achieving 1.2±0.6 mm placement error at 79.0±8.4 mm depth and 2.1±0.7 mm at 156.0±6.9 mm for 2×12 in- and out-of-plane punctures in a gelatin phantom. Conclusions: The system enables precise needle placement in a single insertion and is ready for its first clinical deployment.

A multi-modality tracking, navigation and calibration for a flexible robotic drill system for total hip arthroplasty


Background This paper presents a novel multi-modality tracking and navigation system that provides a unique capability to guild a flexible drill tip inside the bone with accurate curved tunnelling. Methods As the flexible drill tip cannot be tracked optically inside the bone, this research focuses on developing a hybrid tracking and navigation system for tracking a flexible drill tip by using both optical and kinematic tracking. The tracking information is used to guide the THA (total hip arthroplasty) procedure, providing a real-time virtual model of the flexible drill. Results The flexible and steerable drill tip system is then tested on total hip arthroplasty followed by evaluation of the positioning and orientation of femoral stem placement by femoral milling. Conclusions Based on this study, we conclude that the tracking and navigation system is able to guide the flexible drill to mill inside femoral canal.

Robotic Strong's procedure for the treatment of superior mesenteric artery syndrome. Description of surgical technique on occasion of the first reported case in the literature


Backround Superior Mesenteric Artery Syndrome (SMAS) is a rare disorder caused by compression of the third portion of the duodenum by the SMA. Once a conservative approach fails, usual surgical strategies include Duodenojejunostomy and Strong's procedure. The latter avoids potential anastomotic risks and complications. Robotic Strong's procedure (RSP) combines both the benefits of a minimal invasive approach and also enchased robotic accuracy and efficacy. Methods For a young girl who was unsuccessfully treated conservatively, the paper describes the RSP surgical technique. To the authors' knowledge, this is the first report in the literature. Results Minimal blood loss, short operative time, short hospital stay and early recovery were the short-term benefits. Significant weight gain was achieved three months after the surgery. Conclusion Based on primary experience, it is suggested that RSP is a very effective alternative in treating SMAS.

Brain biopsy performed with the RONNA G3 system: a case study on using a novel robotic navigation device for stereotactic neurosurgery


Background Robotic neuronavigation is becoming an important tool for neurosurgeons. We present a case study of a frameless stereotactic biopsy guided by the RONNA G3 robotic neuronavigation system. Methods A 45 year-old patient with a history of vertigo, nausea and vomiting was diagnosed with multiple periventricular lesions. Neurological status was unremarkable. A frameless robotic biopsy of a brain lesion was performed. Results Three tissue samples were obtained. There were no intraoperative or postoperative complications. Histological analysis showed a B-cell lymphoma. After merging the preoperative CT scan with the postoperative MRI and CT scans, the measured error between the planned and the postoperatively measured entry point was 2.24 mm and the measured error between the planned and postoperatively measured target point was 2.33 mm. Conclusions The RONNA G3 robotic system was used to navigate a Sedan brain biopsy needle to take tissue samples and could be a safe and precise tool for brain biopsy.