RobUSt-An Autonomous Robotic Ultrasound System for Medical Imaging

Medical ultrasound (US) systems are widely used for the diagnosis of internal tissues. However, there are challenges associated with acquiring and interpreting US images, such as incorrect US probe placement and limited available spatial information. In this study, we expand the capabilities of medical US imaging using a robotic framework with a high level of autonomy. A 3D camera is used to capture the surface of an anthropomorphic phantom as a point cloud, which is then used for path planning and navigation of the US probe. Robotic positioning of the probe is realised using an impedance controller, which maintains stable contact with the surface during US scanning and compensates for uneven and moving surfaces. Robotic US positioning accuracy is measured to be 1.19 +/- 0.76mm. The mean force along US probe z-direction is measured to be 6.11 +/- 1.18N on static surfaces and 6.63 +/- 2.18N on moving surfaces. Overall lowest measured force of 1.58N demonstrates constant probe-to-surface contact during scanning. Acquired US images are used for the 3D reconstruction and multi-modal visualization of the surface and the inner anatomical structures of the phantom. Finally, K-means clustering is used to segment different tissues. Best segmentation accuracy of the jugular vein according to Jaccard similarity coefficient is measured to be 0.89. With such an accuracy, this system could substantially improve autonomous US acquisition and enhance the diagnostic confidence of clinicians

Collaborative Surgical Robots:Optical Tracking During Endovascular Operations

Endovascular interventions usually require meticulous handling of surgical instruments and constant monitoring of the operating room workspace. To address these challenges, robotic- assisted technologies and tracking techniques are increasingly being developed. Specifically, the limited workspace and potential for a collision between the robot and surrounding dynamic obstacles are important aspects that need to be considered. This article presents a navigation system developed to assist clinicians with the magnetic actuation of endovascular catheters using multiple surgical robots. We demonstrate the actuation of a magnetic catheter in an experimental arterial testbed with dynamic obstacles. The motions and trajectory planning of two six degrees of freedom (6-DoF) robotic arms are established through passive markerguided motion planning. We achieve an overall 3D tracking accuracy of 2.3 ± 0.6 mm for experiments involving dynamic obstacles. We conclude that integrating multiple optical trackers with the online planning of two serial-link manipulators is useful to support the treatment of endovascular diseases and aid clinicians during interventions

The ARMM System-Autonomous Steering of Magnetically-Actuated Catheters:Towards Endovascular Applications

Positioning conventional endovascular catheters is not without risk, and there is a multitude of complications that are associated with their use in manual surgical interventions. By utilizing surgical manipulators, the efficacy of remote-controlled catheters can be investigated in vivo. However, technical challenges, such as the duration of catheterizations, accurate positioning at target sites, and consistent imaging of these catheters using non-hazardous modalities, still exist. In this paper, we propose the integration of multiple sub-systems in order to extend the clinical feasibility of an autonomous surgical system designed to address these challenges. The system handles the full synchronization of co-operating manipulators that both actuate a clinical tool. The experiments within this study are conducted within a clinically-relevant workspace and inside a gelatinous phantom that represents a life-size human torso. A catheter is positioned using magnetic actuation and proportional-integral (PI) control in conjunction with real-time ultrasound images. Our results indicate an average error between the tracked catheter tip and target positions of 2:09 0:49 mm. The median procedure time to reach targets is 32:6 s. We expect that our system will provide a step towards collaborative manipulators employing mobile electromagnets, and possibly improve autonomous catheterization procedures within endovascular surgeries

Design and Evaluation of a Magnetic Rotablation Catheter for Arterial Stenosis

Arterial stenosis is a high-risk disease accompanied by large amounts of calcified deposits and plaques that develop inside the vasculature. These deposits should be reduced to improve blood flow. However, current methods used to reduce stenosis require externally-controlled actuation systems resulting in limited workspace or patient risks. This results in an unexplored preference regarding the revascularization strategy for symptomatic artery stenosis. In this paper, we propose a novel internally-actuated solution: a magnetic spring-loaded rotablation catheter. The catheter is developed to achieve stenosis-debulking capabilities by actuating drill bits using two internal electromagnetic coils and a magnetic reciprocating spring-loaded shaft. The state-space model of the catheter is validated by comparing the simulation results of the magnetic fields of the internal coils with the experimental results of a fabricated prototype. Contact forces of the catheter tip are measured experimentally, resulting in a maximum axial force of 2.63 N and a torque of 5.69 mN-m. Finally, we present interventions in which the catheter is inserted to a vascular target site and demonstrate plaque-specific treatment using different detachable actuator bits. Calcified deposits are debulked and visualized via ultrasound imaging. The catheter can reduce a stenosis cross-sectional area by up to 35%, indicating the potential for the treatment of calcified lesions, which could prevent restenosis

Design, construction and analysis of an alternative stroke rehabilitation device based on the principels of neuroplasticity

Thesis (MEng)--Stellenbosch University, 2016.ENGLISH ABSTRAST: The use of robotics in post-stroke patient rehabilitation and research has increased substantially during the last two decades. However, it has also led to important social and economic concerns, as the number of patients in developing countries that can afford the expensive outpatient rehabilitation, and therefore be treated, are limited. Not much is known about alternative lowcost rehabilitation devices. The motivation behind this thesis is to eventually address two of the most prominent limiting complications in stroke recovery programs, which are the time available for patient engagement, and the cost for outpatient rehabilitation. It presents the experimental design, construction, and analysis of a prototype stroke rehabilitation device, based on the principles of sensory stimulation therapy and neuroplasticity. The main objective of this project was to come to the conclusion whether it is possible to sense different electrobiological potentials in the brain during discrete events, from the constructed wearable sensory feedback device. The device is experimentally tested through the implementation of a case-control observational Event-Related Potential (ERP) study on healthy test subjects. The experimental results demonstrate the detection of cognitive and sensory-motor brain activity in response to, and in anticipation of, a somatic sensation. Electroencephalography (EEG) data is analyzed and decomposed to replicate three different ERPs, namely the P200 exogenous-sensory and -visual component, and the P300 endogenous component. The statistical analysis results indicate that a definite correlation is found between the Visual vs. P200 (F = 1.274, p = 0.28535) and the P200 vs. P300 (F = 64.253; p < 0.001) components when compared to previous ERP studies. The present evidence supports the use of mechanical-assisted therapy and indicates that potentially cost saving alternative rehabilitation techniques are possible in their use of providing sensory feedback, and recording and analyzing EEG feedback.AFRIKAANSE OPSOMMING: Die gebruik van robotika in die rehabilitasie en navorsing van pasiënte na beroerte het gedurende die afgelope twee dekades aansienlik toegeneem. Dit het egter ook gelei tot sekere nadelige sosiale en ekonomiese gevolge, aangesien die aantal pasiënte wat die duur buitepasiënt-rehabilitasie kan bekostig, en dus in effek behandel kan word, afneem. Buitendien is daar min inligting bekend oor alternatiewe laekoste-rehabilitasietoestelle. Die motivering van hierdie tesis is om uiteindelik twee van die mees prominente komplikasies in beroerte herstellingsprogramme, naamlik die tyd wat beskikbaar is vir pasiënt behandeling en die koste verbonde aan buitepasiënt-rehabilitasie, aan te spreek. Hierdie tesis handel oor die proefondervindelike toetsing, ontwikkeling en analisering van ’n lae-koste beroerte-rehabilitasietoestel prototipe, wat op die beginsels van sensoriese stimulasie terapie en neuroplastisiteit berus. Die hoofoogmerk van hierdie projek was om tot gevolgtrekking te kom of dit moontlik is om verskillende elektrobiologiese potensiale wat deur die ontwikkelde draagbare toestel gelewer word, in die brein op te tel tydens diskrete aktiwiteite. Proefondervindelike toetsing op gesonde individue het deur middel van die implementering van ’n geval-gekontroleerde observerende Respons-Verwante Potensiaal (RVP) studie plaasgevind. Die proefondervindelike resultate toon dat kognitiewe en sensories-motoriese breinaktiwiteit opgetel word in reaksie op, en in afwagting van ’n somatiese sensasie. Elektro-ensefalografie (EEG) data is ontleed en voorgestel as drie verskillende RVP’s, naamlik die P200-eksogene-sensoriese en -Visuele komponent, en die P300-endogene komponent. Die statistiese ontleding van die resultate dui aan dat ’n definitiewe korrelasie gevind is tussen die Visuele- teenoor P200-komponent (F = 1,274; p = 0,28535) en die P200- teenoor P300-komponent (F = 64,253; p < 0.001), in vergelyking met vorige soortgelyke RVP-studies. Die huidige bewyse ondersteun die gebruik van meganiese-bystand terapiemetodes en dui aan dat potensiele kostebesparing rehabilitasie-tegnieke moontlik is in die gebruik van verskaffing van sensoriese terugvoer, EEG-terugvoer opnames en ontleding

Intravascular Tracking of Micro-Agents Using Medical Ultrasound: Towards Clinical Applications

Objective: This study demonstrates intravascular micro-agent visualization by utilizing robotic ultrasound-based tracking and visual servoing in clinically-relevant scenarios. Methods: Visual servoing path is planned intraoperatively using a body surface point cloud acquired with a 3D camera and the vessel reconstructed from ultrasound (US) images, where both the camera and the US probe are attached to the robot end-effector. Developed machine vision algorithms are used for detection of micro-agents from minimal size of 250$\boldsymbol{\mu }$m inside the vessel contour and tracking with error recovery. Finally, real-time positions of the micro-agents are used for servoing of the robot with the attached US probe. Constant contact between the US probe and the surface of the body is accomplished by means of impedance control. Results: Breathing motion is compensated to keep constant contact between the US probe and the body surface, with minimal measured force of 2.02 N. Anthropomorphic phantom vessels are segmented with an Intersection-Over-Union (IOU) score of 0.93 $\pm$ 0.05, while micro-agent tracking is performed with up to 99.8% success rate at 28-36 frames per second. Path planning, tracking and visual servoing are realized over 80 mm and 120 mm long surface paths. Conclusion: Experiments performed using anthropomorphic surfaces, biological tissue, simulation of physiological movement and simulation of fluid flow through the vessels indicate that robust visualization and tracking of micro-agents involving human patients is an achievable goal

The ARMM System: An Optimized Mobile Electromagnetic Coil for Non-Linear Actuation of Flexible Surgical Instruments

Automation of flexible surgical instruments requires the development of robotic technologies capable of small-scale power transmission. Magnetic actuation has successfully been used for that purpose. Nevertheless, current systems for magnetic actuation suffer from small workspaces or poor bandwidth of magnetic field control. In this work, we design, develop, and test a novel magnetic actuation system called Advanced Robotics for Magnetic Manipulation (ARMM). The ARMM system employs a 6 DoF mobile electromagnetic coil capable of generating prescribed magnetic fields and gradients. The mobile coil approach allows for easy scaling of the actuation workspace, which depends on the range of robotic arm, and in our case spans up to 1.3 m. Due to limited end-effector payload of the robotic arm used in the ARMM system, the mobile coil has been designed using an optimization routine. For a given mass and heat dissipation constraints, this routine provides the coil geometry that maximizes the average magnetic field generated in the target region. Since the Vacoflux core of the fabricated coil saturates within operational conditions, we propose an actuation strategy employing an online-updated iterative map technique. Using this map, the ARMM system allows for precise generation of prescribed magnetic fields and gradients at the point of interest, while taking into account the effects of the non-linearities due to core saturation. The strategy is validated experimentally, showing the average error of 2.34% for magnetic field and 7.20% for the magnetic field gradient

Intravascular Tracking of Micro-Agents Using Medical Ultrasound:Towards Clinical Applications

Objective: This study demonstrates intravascular micro-agent visualization by utilizing robotic ultrasound-based tracking and visual servoing in clinically-relevant scenarios. Methods: Visual servoing path is planned intraoperatively using a body surface point cloud acquired with a 3D camera and the vessel reconstructed from ultrasound (US) images, where both the camera and the US probe are attached to the robot end-effector. Developed machine vision algorithms are used for detection of micro-agents from minimal size of 250$\boldsymbol{\mu }$m inside the vessel contour and tracking with error recovery. Finally, real-time positions of the micro-agents are used for servoing of the robot with the attached US probe. Constant contact between the US probe and the surface of the body is accomplished by means of impedance control. Results: Breathing motion is compensated to keep constant contact between the US probe and the body surface, with minimal measured force of 2.02 N. Anthropomorphic phantom vessels are segmented with an Intersection-Over-Union (IOU) score of 0.93 $\pm$ 0.05, while micro-agent tracking is performed with up to 99.8% success rate at 28-36 frames per second. Path planning, tracking and visual servoing are realized over 80 mm and 120 mm long surface paths. Conclusion: Experiments performed using anthropomorphic surfaces, biological tissue, simulation of physiological movement and simulation of fluid flow through the vessels indicate that robust visualization and tracking of micro-agents involving human patients is an achievable goal

Real-time multi-modal sensing and feedback for catheterization in porcine tissue

Objective: In this study, we introduce a multi-modal sensing and feedback framework aimed at assisting clinicians during endovascular surgeries and catheterization procedures. This framework utilizes state-of-the-art imaging and sensing sub-systems to produce a 3D visualization of an endovascular catheter and surrounding vasculature without the need for intra-operative X-rays. Methods: The catheterization experiments within this study are conducted inside a porcine limb undergoing motions. A hybrid position-force controller of a robotically-actuated ultrasound (US) transducer for uneven porcine tissue surfaces is introduced. The tissue, vasculature, and catheter are visualized by integrated real-time US images, 3D surface imaging, and Fiber Bragg Grating (FBG) sensors. Results: During externally-induced limb motions, the vasculature and catheter can be reliably reconstructed at mean accuracies of 1.9 ± 0.3 mm and 0.82 ± 0.21 mm, respectively. Conclusions: The conventional use of intra-operative X-ray imaging to visualize instruments and vasculature in the human body can be reduced by employing improved diagnostic technologies that do not operate via ionizing radiation or nephrotoxic contrast agents. Significance: The presented multi-modal framework enables the radiation-free and accurate reconstruction of significant tissues and instruments involved in catheterization procedures