An open electromagnetic tracking framework applied to targeted liver tumour ablation

Purpose: Electromagnetic tracking is a core platform technology in the navigation and visualisation of image-guided procedures. The technology provides high tracking accuracy in non-line-of-sight environments, allowing instrument navigation in locations where optical tracking is not feasible. EMT can be beneficial in applications such as percutaneous radiofrequency ablation for the treatment of hepatic lesions where the needle tip may be obscured due to difficult liver environments (e.g subcutaneous fat or ablation artefacts). Advances in the field of EMT include novel methods of improving tracking system accuracy, precision and error compensation capabilities, though such system-level improvements cannot be readily incorporated in current therapy applications due to the ‘blackbox’ nature of commercial tracking solving algorithms. Methods: This paper defines a software framework to allow novel EMT designs, and improvements become part of the global design process for image-guided interventions. An exemplary framework is implemented in the Python programming language and demonstrated with the open-source Anser EMT system. The framework is applied in the preclinical setting though targeted liver ablation therapy on an animal model. Results: The developed framework was tested with the Anser EMT electromagnetic tracking platform. Liver tumour targeting was performed using the tracking framework with the CustusX navigation platform using commercially available electromagnetically tracked needles. Ablation of two tumours was performed with a commercially available ablation system. Necropsy of the tumours indicated ablations within 5 mm of the tumours. Conclusions: An open-source framework for electromagnetic tracking was presented and effectively demonstrated in the preclinical setting. We believe that this framework provides a structure for future advancement in EMT system in and customised instrument design

Peripheral tumour targeting using open-source virtual bronchoscopy with electromagnetic tracking: a multi-user pre-clinical study

Objectives: The goal was to demonstrate the utility of open-source tracking and visualisation tools in the targeting of lung cancer. Material and methods: The study demonstrates the first deployment of the Anser electromagnetic (EM) tracking system with the CustusX image-guided interventional research platform to navigate using an endobronchial catheter to injected tumour targets. Live animal investigations validated the deployment and targeting of peripheral tumour models using an innovative tumour marking routine. Results: Novel tumour model deployment was successfully achieved at all eight target sites across two live animal investigations without pneumothorax. Virtual bronchoscopy with tracking successfully guided the tracked catheter to 2–12 mm from the target tumour site. Deployment of a novel marker was achieved at all eight sites providing a reliable measure of targeting accuracy. Targeting accuracy within 10 mm was achieved in 7/8 sites and in all cases, the virtual target distance at marker deployment was within the range subsequently measured with x-ray. Conclusions: Endobronchial targeting of peripheral airway targets is feasible using existing open-source technology. Notwithstanding the shortcomings of current commercial platforms, technological improvements in EM tracking and registration accuracy fostered by open-source technology may provide the impetus for widespread clinical uptake of electromagnetic navigation in bronchoscopy

Electromagnetic tracking using modular, tiled field generators

Electromagnetic tracking (EMT) systems play an important role in medicine, robotics, and virtual reality applications by providing accurate position and orientation referencing within a fixed volume around a magnetic field generator. Advances in sensor technology provide increasingly small, lightweight sensors capable of being integrated into hand-held devices for medical simulation, gaming, and image-guided surgery. The need for customizable tracking volumes becomes of interest as the uptake of EMT technology increases. This paper proposes a new method of creating custom tracking volumes from multiple planar field generators. A monolithic, low-cost printed circuit board design allows for tiling of multiple generators to create a larger tracking volume. Experiments were performed with two generators at different angles. Successful tracking is demonstrated with increased positional accuracy observed when transmitters are inclined with respect to one another. Horizontal tiling configurations are most accurate when a common edge is shared between adjacent field generators

Desarrollo de un nuevo sistema de navegación en Implantología basado en unidades de medición inercial

La colocación de implantes dentales mediante cirugía guiada por ordenador tiene numerosas ventajas frente a la realizada a mano alzada, especialmente mayor precisión, mayor seguridad y menor invasividad. Pero también, tanto los sistemas estáticos o férulas, como los dinámicos o navegación, presentan dificultades de uso y un mayor coste, por lo que su utilización actual es limitada. Se elabora una revisión de los distintos sistemas de guiado de la cirugía de colocación de implantes, de su uso, precisión y fuentes de error. Describimos la unidad de medición inercial o IMU y sus primeras aplicaciones en cirugía general, como una alternativa versátil, simple y económica a las tecnologías existentes. Por medio de un prototipo que integra los sensores IMU en una interfaz computerizada, se colocan implantes guiados por estos sensores, y también por férulas CAD-CAM. Los resultados medios comparados que obtenemos entre ambos sistemas de guiado, son similares estadísticamente. Las desviaciones medias han sido en coronal 1.48 ± 0.2 (SD 0.58; 95% CI 1.27 - 1.69) y 1.42 ± 0.2 (SD 0.61; 95% CI 1.2 - 1.64) mm, en apical 2.00 ± 0.33 (SD 0.93; 95% CI 1.67 - 2.33) y 2.07 ± 0.35 (SD 0.97; 95% CI 1.72 - 2.42) mm, y las angulares 7.13º ± 1.47º (SD 4.1; 95% CI 5.66 - 8.6) y 5.63º ± 1.41º (SD 3.94; 95% CI 4.22 - 7.04), para IMU y Férulas Estereolitográficas (FE) respectivamente. Estos resultados son consistentes con la precisión reportada en la literatura para la cirugía guiada, tanto estática como dinámica. Se valora igualmente la percepción del operador y su comodidad de uso, encontrando que el manejo del sistema requiere un entrenamiento previo y que se facilitaría al mejorar la interfaz gráfica. Se abre así una vía de investigación para adaptar este nuevo sistema de navegación al uso clínico rutinario. Para ello, es necesaria la mejora in vitro de sus condiciones de manejo, así como ulteriores estudios sobre pacientes.Computer-guided dental implant placement is considered to be safer, more accurate and less invasive compared to freehand implant surgery. Currently two types of surgical guiding systems are available, static templates and dynamic navigation. Both make intervention more complex and costly and this could be the reason why their current use remains limited. A "state of the art" of the different implant placement guiding systems, their use, precision and sources of error has been conducted. The Inertial Measurement Unit (IMU) and its early applications in general surgery are described. The IMU was shown to be a versatile, simple and economical alternative to existing surgical guidance technologies. A prototype surgical handpiece was assembled with IMU sensors integrated with a computerized interface to guide implant placement. Implants were placed in models using this prototype and the standard CAD-CAM splints. Similar statistical average results were obtained using either of the two systems. The mean deviations were 1.48 ± 0.2 (SD 0.58; 95% CI 1.27 - 1.69) and 1.42 ± 0.2 (SD 0.61; 95% CI 1.2 - 1.64) mm coronal, 2.00 ± 0.33 (SD 0.93; 95% CI 1.67 - 2.33) and 2.07 ± 0.35 (SD 0.97; 95% CI 1.72 - 2.42) mm apical, and 7.13º ± 1.47º (SD 4.1; 95% CI 5.66 - 8.6) y 5.63º ± 1.41º (SD 3.94; 95% CI 4.22 - 7.04) angular, for IMU’s and splints respectively. These results are consistent with the precision reported in the literature for guided surgery, both current static and dynamic modalities. When operator’s perceptions and comfort of use were addressed, it was found that the system’s handling requires going through a learning curve and that it would be facilitated by improving the graphic interface. The present study opens a path of investigation to adapt this new surgical navigation system to routine clinical use. To this end, the system has to be improved to make the operator’s control easier before further studies on patients can be carried out

Surgical Instruments based on flexible micro-electronics

This dissertation explores strategies to create micro-scale tools with integrated electronic and mechanical functionalities. Recently developed approaches to control the shape of flexible micro-structures are employed to fabricate micro-electronic instruments that embed components for sensing and actuation, aiming to expand the toolkit of minimally invasive surgery. This thesis proposes two distinct types of devices that might expand the boundaries of modern surgical interventions and enable new bio-medical applications. First, an electronically integrated micro-catheter is developed. Electronic components for sensing and actuation are embedded into the catheter wall through an alternative fabrication paradigm that takes advantage of a self-rolling polymeric thin-film system. With a diameter of only 0.1 mm, the catheter is capable of delivering fluids in a highly targeted fashion, comprises actuated opposing digits for the efficient manipulation of microscopic objects, and a magnetic sensor for navigation. Employing a specially conceived approach for position tracking, navigation with a high resolution below 0.1 mm is achieved. The fundamental functionalities and mechanical properties of this instrument are evaluated in artificial model environments and ex vivo tissues. The second development explores reshapeable micro-electronic devices. These systems integrate conductive polymer actuators and strain or magnetic sensors to adjust their shape through feedback-driven closed loop control and mechanically interact with their environment. Due to their inherent flexibility and integrated sensory capabilities, these devices are well suited to interface with and manipulate sensitive biological tissues, as demonstrated with an ex vivo nerve bundle, and may facilitate new interventions in neural surgery.:List of Abbreviations 1 Introduction 1.1 Motivation 1.2 Objectives and structure of this dissertation 2 Background 2.1 Tools for minimally invasive surgery 2.1.1 Catheters 2.1.2 Tools for robotic micro-surgery 2.1.3 Flexible electronics for smart surgical tools 2.2 Platforms for shapeable electronics 2.2.1 Shapeable polymer composites 2.2.2 Shapeable electronics 2.2.3 Soft actuators and manipulators 2.3 Sensors for position and shape feedback 2.3.1 Magnetic sensors for position and orientation measurements 2.3.2 Strain gauge sensors 3 Materials and Methods 3.1 Materials for shapeable electronics 3.1.1 Metal-organic sacrificial layer 3.1.2 Polyimide as reinforcing material 3.1.3 Swelling hydrogel for self assembly 3.1.4 Polypyrrole for flexible micro actuators 3.2 Device fabrication techniques 3.2.1 Photolithography 3.2.2 Electron beam deposition 3.2.3 Sputter deposition 3.2.4 Atomic layer deposition 3.2.5 Electro-polymerization of polypyrrole 3.3 Device characterization techniques 3.3.1 Kerr magnetometry 3.3.2 Electro-magnetic characterization of sensors 3.3.3 Electro-chemical analysis of polypyrrole 3.3.4 Preparation of model environments and materials 3.4 Sensor signal evaluation and processing 3.4.1 Signal processing 3.4.2 Cross correlation for phase analysis 3.4.3 PID feedback control 4 Electronically Integrated Self Assembled Micro Catheters 4.1 Design and Fabrication 4.1.1 Fabrication and self assembly 4.1.2 Features and design considerations 4.1.3 Electronic and fluidic connections 4.2 Integrated features and functionalities 4.2.1 Fluidic transport 4.2.2 Bending stability 4.2.3 Actuated micro manipulator 4.3 Magnetic position tracking 4.3.1 Integrated magnetic sensor 4.3.2 Position control with sensor feedback 4.3.3 Introduction of magnetic phase encoded tracking 4.3.4 Experimental realization 4.3.5 Simultaneous magnetic and ultrasound tracking 4.3.6 Discussion, limitations, and perspectives 5 Reshapeable Micro Electronic Devices 5.1 Design and fabrication 5.1.1 Estimation of optimal fabrication parameters 5.1.2 Device Fabrication 5.1.3 Control electronics and software 5.2 Performance of Actuators 5.2.1 Blocking force, speed, and durability 5.2.2 Curvature 5.3 Orientation control with magnetic sensors 5.3.1 Magnetic sensors on actuated device 5.3.2 Reference magnetic field 5.3.3 Feedback control 5.4 Shape control with integrated strain sensors 5.4.1 Strain gauge curvature sensors 5.4.2 Feedback control 5.4.3 Obstacle detection 5.5 Heterogenous integration with active electronics 5.5.1 Fabrication and properties of active matrices 5.5.2 Fabrication and operation of PPy actuators 5.5.3 Site selective actuation 6 Discussion and Outlook 6.1 Integrated self assembled catheters 6.1.1 Outlook 6.2 Reshapeable micro electronic devices 6.2.1 Outlook 7 Conclusion Appendix A1 Processing parameters for polymer stack layers A2 Derivation of magnetic phase profile in 3D Bibliography List of Figures and Tables Acknowledgements Theses List of Publication

Mechatronic Systems

Mechatronics, the synergistic blend of mechanics, electronics, and computer science, has evolved over the past twenty five years, leading to a novel stage of engineering design. By integrating the best design practices with the most advanced technologies, mechatronics aims at realizing high-quality products, guaranteeing at the same time a substantial reduction of time and costs of manufacturing. Mechatronic systems are manifold and range from machine components, motion generators, and power producing machines to more complex devices, such as robotic systems and transportation vehicles. With its twenty chapters, which collect contributions from many researchers worldwide, this book provides an excellent survey of recent work in the field of mechatronics with applications in various fields, like robotics, medical and assistive technology, human-machine interaction, unmanned vehicles, manufacturing, and education. We would like to thank all the authors who have invested a great deal of time to write such interesting chapters, which we are sure will be valuable to the readers. Chapters 1 to 6 deal with applications of mechatronics for the development of robotic systems. Medical and assistive technologies and human-machine interaction systems are the topic of chapters 7 to 13.Chapters 14 and 15 concern mechatronic systems for autonomous vehicles. Chapters 16-19 deal with mechatronics in manufacturing contexts. Chapter 20 concludes the book, describing a method for the installation of mechatronics education in schools

Improving the efficiency and accuracy of nocturnal bird Surveys through equipment selection and partial automation

This thesis was submitted for the degree of Engineering Doctorate and awarded by Brunel University.Birds are a key environmental asset and this is recognised through comprehensive legislation and policy ensuring their protection and conservation. Many species are active at night and surveys are required to understand the implications of proposed developments such as towers and reduce possible conflicts with these structures. Night vision devices are commonly used in nocturnal surveys, either to scope an area for bird numbers and activity, or in remotely sensing an area to determine potential risk. This thesis explores some practical and theoretical approaches that can improve the accuracy, confidence and efficiency of nocturnal bird surveillance. As image intensifiers and thermal imagers have operational differences, each device has associated strengths and limitations. Empirical work established that image intensifiers are best used for species identification of birds against the ground or vegetation. Thermal imagers perform best in detection tasks and monitoring bird airspace usage. The typically used approach of viewing bird survey video from remote sensing in its entirety is a slow, inaccurate and inefficient approach. Accuracy can be significantly improved by viewing the survey video at half the playback speed. Motion detection efficiency and accuracy can be greatly improved through the use of adaptive background subtraction and cumulative image differencing. An experienced ornithologist uses bird flight style and wing oscillations to identify bird species. Changes in wing oscillations can be represented in a single inter-frame similarity matrix through area-based differencing. Bird species classification can then be automated using singular value decomposition to reduce the matrices to one-dimensional vectors for training a feed-forward neural network

Research and technology highlights, 1993

This report contains highlights of the major accomplishments and applications that have been made by Langley researchers and by our university and industry colleagues during the past year. The highlights illustrate both the broad range of the research and technology activities supported by NASA Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research. This report also describes some of the Center's most important research and testing facilities