270 research outputs found
Advanced tracking and image registration techniques for intraoperative radiation therapy
Mención Internacional en el título de doctorIntraoperative electron radiation therapy (IOERT) is a technique used to
deliver radiation to the surgically opened tumor bed without irradiating healthy
tissue. Treatment planning systems and mobile linear accelerators enable
clinicians to optimize the procedure, minimize stress in the operating room (OR)
and avoid transferring the patient to a dedicated radiation room. However,
placement of the radiation collimator over the tumor bed requires a validation
methodology to ensure correct delivery of the dose prescribed in the treatment
planning system. In this dissertation, we address three well-known limitations of
IOERT: applicator positioning over the tumor bed, docking of the mobile linear
accelerator gantry with the applicator and validation of the dose delivery
prescribed. This thesis demonstrates that these limitations can be overcome by
positioning the applicator appropriately with respect to the patient’s anatomy.
The main objective of the study was to assess technological and procedural
alternatives for improvement of IOERT performance and resolution of
problems of uncertainty. Image-to-world registration, multicamera optical
trackers, multimodal imaging techniques and mobile linear accelerator docking
are addressed in the context of IOERT.
IOERT is carried out by a multidisciplinary team in a highly complex
environment that has special tracking needs owing to the characteristics of its
working volume (i.e., large and prone to occlusions), in addition to the requisites
of accuracy. The first part of this dissertation presents the validation of a
commercial multicamera optical tracker in terms of accuracy, sensitivity to
miscalibration, camera occlusions and detection of tools using a feasible surgical
setup. It also proposes an automatic miscalibration detection protocol that
satisfies the IOERT requirements of automaticity and speed. We show that the
multicamera tracker is suitable for IOERT navigation and demonstrate the
feasibility of the miscalibration detection protocol in clinical setups.
Image-to-world registration is one of the main issues during image-guided
applications where the field of interest and/or the number of possible
anatomical localizations is large, such as IOERT. In the second part of this
dissertation, a registration algorithm for image-guided surgery based on lineshaped
fiducials (line-based registration) is proposed and validated. Line-based registration decreases acquisition time during surgery and enables better
registration accuracy than other published algorithms.
In the third part of this dissertation, we integrate a commercial low-cost
ultrasound transducer and a cone beam CT C-arm with an optical tracker for
image-guided interventions to enable surgical navigation and explore image based
registration techniques for both modalities.
In the fourth part of the dissertation, a navigation system based on optical
tracking for the docking of the mobile linear accelerator to the radiation
applicator is assessed. This system improves safety and reduces procedure time.
The system tracks the prescribed collimator location to solve the movements
that the linear accelerator should perform to reach the docking position and
warns the user about potentially unachievable arrangements before the actual
procedure. A software application was implemented to use this system in the
OR, where it was also evaluated to assess the improvement in docking speed.
Finally, in the last part of the dissertation, we present and assess the
installation setup for a navigation system in a dedicated IOERT OR, determine
the steps necessary for the IOERT process, identify workflow limitations and
evaluate the feasibility of the integration of the system in a real OR. The
navigation system safeguards the sterile conditions of the OR, clears the space
available for surgeons and is suitable for any similar dedicated IOERT OR.La Radioterapia Intraoperatoria por electrones (RIO) consiste en la
aplicación de radiación de alta energía directamente sobre el lecho tumoral,
accesible durante la cirugía, evitando radiar los tejidos sanos. Hoy en día, avances
como los sistemas de planificación (TPS) y la aparición de aceleradores lineales
móviles permiten optimizar el procedimiento, minimizar el estrés clínico en el
entorno quirúrgico y evitar el desplazamiento del paciente durante la cirugía a
otra sala para ser radiado. La aplicación de la radiación se realiza mediante un
colimador del haz de radiación (aplicador) que se coloca sobre el lecho tumoral
de forma manual por el oncólogo radioterápico. Sin embargo, para asegurar una
correcta deposición de la dosis prescrita y planificada en el TPS, es necesaria una
adecuada validación de la colocación del colimador. En esta Tesis se abordan
tres limitaciones conocidas del procedimiento RIO: el correcto posicionamiento
del aplicador sobre el lecho tumoral, acoplamiento del acelerador lineal con el
aplicador y validación de la dosis de radiación prescrita. Esta Tesis demuestra
que estas limitaciones pueden ser abordadas mediante el posicionamiento del
aplicador de radiación en relación con la anatomía del paciente.
El objetivo principal de este trabajo es la evaluación de alternativas
tecnológicas y procedimentales para la mejora de la práctica de la RIO y resolver
los problemas de incertidumbre descritos anteriormente. Concretamente se
revisan en el contexto de la radioterapia intraoperatoria los siguientes temas: el
registro de la imagen y el paciente, sistemas de posicionamiento multicámara,
técnicas de imagen multimodal y el acoplamiento del acelerador lineal móvil.
El entorno complejo y multidisciplinar de la RIO precisa de necesidades
especiales para el empleo de sistemas de posicionamiento como una alta
precisión y un volumen de trabajo grande y propenso a las oclusiones de los
sensores de posición. La primera parte de esta Tesis presenta una exhaustiva
evaluación de un sistema de posicionamiento óptico multicámara comercial.
Estudiamos la precisión del sistema, su sensibilidad a errores cometidos en la
calibración, robustez frente a posibles oclusiones de las cámaras y precisión en
el seguimiento de herramientas en un entorno quirúrgico real. Además,
proponemos un protocolo para la detección automática de errores por calibración que satisface los requisitos de automaticidad y velocidad para la RIO
demostrando la viabilidad del empleo de este sistema para la navegación en RIO.
Uno de los problemas principales de la cirugía guiada por imagen es el
correcto registro de la imagen médica y la anatomía del paciente en el quirófano.
En el caso de la RIO, donde el número de posibles localizaciones anatómicas es
bastante amplio, así como el campo de trabajo es grande se hace necesario
abordar este problema para una correcta navegación. Por ello, en la segunda
parte de esta Tesis, proponemos y validamos un nuevo algoritmo de registro
(LBR) para la cirugía guiada por imagen basado en marcadores lineales. El
método propuesto reduce el tiempo de la adquisición de la posición de los
marcadores durante la cirugía y supera en precisión a otros algoritmos de registro
establecidos y estudiados en la literatura.
En la tercera parte de esta tesis, integramos un transductor de ultrasonido
comercial de bajo coste, un arco en C de rayos X con haz cónico y un sistema
de posicionamiento óptico para intervenciones guiadas por imagen que permite
la navegación quirúrgica y exploramos técnicas de registro de imagen para ambas
modalidades.
En la cuarta parte de esta tesis se evalúa un navegador basado en el sistema
de posicionamiento óptico para el acoplamiento del acelerador lineal móvil con
aplicador de radiación, mejorando la seguridad y reduciendo el tiempo del propio
acoplamiento. El sistema es capaz de localizar el colimador en el espacio y
proporcionar los movimientos que el acelerador lineal debe realizar para alcanzar
la posición de acoplamiento. El sistema propuesto es capaz de advertir al usuario
de aquellos casos donde la posición de acoplamiento sea inalcanzable. El sistema
propuesto de ayuda para el acoplamiento se integró en una aplicación software
que fue evaluada para su uso final en quirófano demostrando su viabilidad y la
reducción de tiempo de acoplamiento mediante su uso.
Por último, presentamos y evaluamos la instalación de un sistema de
navegación en un quirófano RIO dedicado, determinamos las necesidades desde
el punto de vista procedimental, identificamos las limitaciones en el flujo de
trabajo y evaluamos la viabilidad de la integración del sistema en un entorno
quirúrgico real. El sistema propuesto demuestra ser apto para el entorno RIO
manteniendo las condiciones de esterilidad y dejando despejado el campo
quirúrgico además de ser adaptable a cualquier quirófano similar.Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Raúl San José Estépar.- Secretario: María Arrate Muñoz Barrutia.- Vocal: Carlos Ferrer Albiac
Autonomous Medical Needle Steering In Vivo
The use of needles to access sites within organs is fundamental to many
interventional medical procedures both for diagnosis and treatment. Safe and
accurate navigation of a needle through living tissue to an intra-tissue target
is currently often challenging or infeasible due to the presence of anatomical
obstacles in the tissue, high levels of uncertainty, and natural tissue motion
(e.g., due to breathing). Medical robots capable of automating needle-based
procedures in vivo have the potential to overcome these challenges and enable
an enhanced level of patient care and safety. In this paper, we show the first
medical robot that autonomously navigates a needle inside living tissue around
anatomical obstacles to an intra-tissue target. Our system leverages an aiming
device and a laser-patterned highly flexible steerable needle, a type of needle
capable of maneuvering along curvilinear trajectories to avoid obstacles. The
autonomous robot accounts for anatomical obstacles and uncertainty in living
tissue/needle interaction with replanning and control and accounts for
respiratory motion by defining safe insertion time windows during the breathing
cycle. We apply the system to lung biopsy, which is critical in the diagnosis
of lung cancer, the leading cause of cancer-related death in the United States.
We demonstrate successful performance of our system in multiple in vivo porcine
studies and also demonstrate that our approach leveraging autonomous needle
steering outperforms a standard manual clinical technique for lung nodule
access.Comment: 22 pages, 6 figure
Neurosurgical Ultrasound Pose Estimation Using Image-Based Registration and Sensor Fusion - A Feasibility Study
Modern neurosurgical procedures often rely on computer-assisted real-time guidance using multiple medical imaging modalities. State-of-the-art commercial products enable the fusion of pre-operative with intra-operative images (e.g., magnetic resonance [MR] with ultrasound [US] images), as well as the on-screen visualization of procedures in progress. In so doing, US images can be employed as a template to which pre-operative images can be registered, to correct for anatomical changes, to provide live-image feedback, and consequently to improve confidence when making resection margin decisions near eloquent regions during tumour surgery.
In spite of the potential for tracked ultrasound to improve many neurosurgical procedures, it is not widely used. State-of-the-art systems are handicapped by optical tracking’s need for consistent line-of-sight, keeping tracked rigid bodies clean and rigidly fixed, and requiring a calibration workflow. The goal of this work is to improve the value offered by co-registered ultrasound images without the workflow drawbacks of conventional systems. The novel work in this thesis includes: the exploration and development of a GPU-enabled 2D-3D multi-modal registration algorithm based on the existing LC2 metric; and the use of this registration algorithm in the context of a sensor and image-fusion algorithm.
The work presented here is a motivating step in a vision towards a heterogeneous tracking framework for image-guided interventions where the knowledge from intraoperative imaging, pre-operative imaging, and (potentially disjoint) wireless sensors in the surgical field are seamlessly integrated for the benefit of the surgeon. The technology described in this thesis, inspired by advances in robot localization demonstrate how inaccurate pose data from disjoint sources can produce a localization system greater than the sum of its parts
Automated catheter navigation with electromagnetic image guidance
This paper describes a novel method of controlling an endoscopic catheter by using an automated catheter tensioning system with the objective of providing clinicians with improved manipulation capabilities within the patient. Catheters are used in many clinical procedures to provide access to the cardiopulmonary system. Control of such catheters is performed manually by the clinicians using a handle, typically actuating a single or opposing set of pull wires. Such catheters are generally actuated in a single plane, requiring the clinician to rotate the catheter handle to navigate the system. The automation system described here allows closed-loop control of a custom bronchial catheter in tandem with an electromagnetic tracking of the catheter tip and image guidance by using a 3D Slicer. An electromechanical drive train applies tension to four pull wires to steer the catheter tip, with the applied force constantly monitored through force sensing load cells. The applied tension is controlled through a PC connected joystick. An electromagnetic sensor embedded in the catheter tip enables constant real-time position tracking, whereas a working channel provides a route for endoscopic instruments. The system is demonstrated and tested in both a breathing lung model and a preclinical animal study. Navigation to predefined targets in the subject's airways by using the joystick while using virtual image guidance and electromagnetic tracking was demonstrated. Average targeting times were 29 and 10 s, respectively, for the breathing lung and live animal studies. This paper presents the first reported remote controlled bronchial working channel catheter utilizing electromagnetic tracking and has many implications for future development in endoscopic and catheter-based procedures
Medical Robotics
The first generation of surgical robots are already being installed in a number of operating rooms around the world. Robotics is being introduced to medicine because it allows for unprecedented control and precision of surgical instruments in minimally invasive procedures. So far, robots have been used to position an endoscope, perform gallbladder surgery and correct gastroesophogeal reflux and heartburn. The ultimate goal of the robotic surgery field is to design a robot that can be used to perform closed-chest, beating-heart surgery. The use of robotics in surgery will expand over the next decades without any doubt. Minimally Invasive Surgery (MIS) is a revolutionary approach in surgery. In MIS, the operation is performed with instruments and viewing equipment inserted into the body through small incisions created by the surgeon, in contrast to open surgery with large incisions. This minimizes surgical trauma and damage to healthy tissue, resulting in shorter patient recovery time. The aim of this book is to provide an overview of the state-of-art, to present new ideas, original results and practical experiences in this expanding area. Nevertheless, many chapters in the book concern advanced research on this growing area. The book provides critical analysis of clinical trials, assessment of the benefits and risks of the application of these technologies. This book is certainly a small sample of the research activity on Medical Robotics going on around the globe as you read it, but it surely covers a good deal of what has been done in the field recently, and as such it works as a valuable source for researchers interested in the involved subjects, whether they are currently “medical roboticists” or not
Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery
One of the main challenges for computer-assisted surgery (CAS) is to determine the intra-opera- tive morphology and motion of soft-tissues. This information is prerequisite to the registration of multi-modal patient-specific data for enhancing the surgeon’s navigation capabilites by observ- ing beyond exposed tissue surfaces and for providing intelligent control of robotic-assisted in- struments. In minimally invasive surgery (MIS), optical techniques are an increasingly attractive approach for in vivo 3D reconstruction of the soft-tissue surface geometry. This paper reviews the state-of-the-art methods for optical intra-operative 3D reconstruction in laparoscopic surgery and discusses the technical challenges and future perspectives towards clinical translation. With the recent paradigm shift of surgical practice towards MIS and new developments in 3D opti- cal imaging, this is a timely discussion about technologies that could facilitate complex CAS procedures in dynamic and deformable anatomical regions
- …