1,606 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
The management of imaging dose during imageâ guided radiotherapy: Report of the AAPM Task Group 75
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134823/1/mp5667.pd
Advances in navigation and intraoperative imaging for intraoperative electron radiotherapy
Mención Internacional en el título de doctorEsta tesis se enmarca dentro del campo de la radioterapia y trata específicamente sobre
la radioterapia intraoperatoria (RIO) con electrones. Esta técnica combina la resección
quirúrgica de un tumor y la radiación terapéutica directamente aplicada sobre el lecho
tumoral post-resección o sobre el tumor no resecado. El haz de electrones de alta
energía es colimado y conducido por un aplicador específico acoplado a un acelerador
lineal. La planificación de la RIO con electrones es compleja debido a las
modificaciones geométricas y anatómicas producidas por la retracción de estructuras y
la eliminación de tejidos cancerosos durante la cirugía. Actualmente, no se dispone del
escenario real en este tipo de tratamientos (por ejemplo, la posición/orientación del
aplicador respecto a la anatomía del paciente o las irregularidades en la superficie
irradiada), sólo de una estimación grosso modo del tratamiento real administrado al
paciente. Las imágenes intraoperatorias del escenario real durante el tratamiento
(concretamente imágenes de tomografía axial computarizada [TAC]) serían útiles no
sólo para la planificación intraoperatoria, sino también para registrar y evaluar el
tratamiento administrado al paciente. Esta información es esencial en estudios
prospectivos.
En esta tesis se evaluó en primer lugar la viabilidad de un sistema de seguimiento
óptico de varias cámaras para obtener la posición/orientación del aplicador en los
escenarios de RIO con electrones. Los resultados mostraron un error de posición del
aplicador inferior a 2 mm (error medio del centro del bisel) y un error de orientación
menor de 2º (error medio del eje del bisel y del eje longitudinal del aplicador). Estos
valores están dentro del rango propuesto por el Grupo de Trabajo 147 (encargo del
Comité de Terapia y del Subcomité para la Mejora de la Garantía de Calidad y
Resultados de la Asociación Americana de Físicos en Medicina [AAPM] para estudiar
en radioterapia externa la exactitud de la localización con métodos no radiográficos,
como los sistemas infrarrojos). Una limitación importante de la solución propuesta es
que el aplicador se superpone a la imagen preoperatoria del paciente. Una imagen intraoperatoria proporcionaría información anatómica actualizada y permitiría estimar
la distribución tridimensional de la dosis.
El segundo estudio específico de esta tesis evaluó la viabilidad de adquirir con un TAC
simulador imágenes TAC intraoperatorias de escenarios reales de RIO con electrones.
No hubo complicaciones en la fase de transporte del paciente utilizando la camilla y su
acople para el transporte, o con la adquisición de imágenes TAC intraoperatorias en la
sala del TAC simulador. Los estudios intraoperatorios adquiridos se utilizaron para
evaluar la mejora obtenida en la estimación de la distribución de dosis en comparación
con la obtenida a partir de imágenes TAC preoperatorias, identificando el factor
dominante en esas estimaciones (la región de aire y las irregularidades en la superficie,
no las heterogeneidades de los tejidos).
Por último, el tercer estudio específico se centró en la evaluación de varias tecnologías
TAC de kilovoltaje, aparte del TAC simulador, para adquirir imágenes intraoperatorias
con las que estimar la distribución de la dosis en RIO con electrones. Estos dispositivos
serían necesarios en el caso de disponer de aceleradores lineales portátiles en el
quirófano ya que no se aprobaría mover al paciente a la sala del TAC simulador. Los
resultados con un maniquí abdominal mostraron que un TAC portátil (BodyTom) e
incluso un acelerador lineal con un TAC de haz de cónico (TrueBeam) serían
adecuados para este propósito.This thesis is framed within the field of radiotherapy, specifically intraoperative
electron radiotherapy (IOERT). This technique combines surgical resection of a tumour
and therapeutic radiation directly applied to a post-resection tumour bed or to an
unresected tumour. The high-energy electron beam is collimated and conducted by a
specific applicator docked to a linear accelerator (LINAC). Dosimetry planning for
IOERT is challenging owing to the geometrical and anatomical modifications produced
by the retraction of structures and removal of cancerous tissues during the surgery. No
data of the actual IOERT 3D scenario is available (for example, the applicator pose in
relation to the patient’s anatomy or the irregularities in the irradiated surface) and
consequently only a rough approximation of the actual IOERT treatment administered
to the patient can be estimated. Intraoperative computed tomography (CT) images of
the actual scenario during the treatment would be useful not only for intraoperative
planning but also for registering and evaluating the treatment administered to the
patient. This information is essential for prospective trials.
In this thesis, the feasibility of using a multi-camera optical tracking system to obtain
the applicator pose in IOERT scenarios was firstly assessed. Results showed that the
accuracy of the applicator pose was below 2 mm in position (mean error of the bevel
centre) and 2º in orientation (mean error of the bevel axis and the longitudinal axis),
which are within the acceptable range proposed in the recommendation of Task Group
147 (commissioned by the Therapy Committee and the Quality Assurance and
Outcomes Improvement Subcommittee of the American Association of Physicists in
Medicine [AAPM] to study the localization accuracy with non-radiographic methods
such as infrared systems in external beam radiation therapy). An important limitation
of this solution is that the actual pose of applicator is superimposed on a patient’s
preoperative image. An intraoperative image would provide updated anatomical
information and would allow estimating the 3D dose distribution.
The second specific study of this thesis evaluated the feasibility of acquiring
intraoperative CT images with a CT simulator in real IOERT scenarios. There were no
complications in the whole procedure related to the transport step using the subtable
and its stretcher or the acquisition of intraoperative CT images in the CT simulator
room. The acquired intraoperative studies were used to evaluate the improvement
achieved in the dose distribution estimation when compared to that obtained from
preoperative CT images, identifying the dominant factor in those estimations (air gap
and the surface irregularities, not tissue heterogeneities).
Finally, the last specific study focused on assessing several kilovoltage (kV) CT
technologies other than CT simulators to acquire intraoperative images for estimating
IOERT dose distribution. That would be necessary when a mobile electron LINAC was
available in the operating room as transferring the patient to the CT simulator room
could not be approved. Our results with an abdominal phantom revealed that a portable
CT (BodyTom) and even a LINAC with on-board kV cone-beam CT (TrueBeam)
would be suitable for this purpose.Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Joaquín López Herráiz.- Secretario: María Arrate Muñoz Barrutia.- Vocal: Óscar Acosta Tamay
Advanced Endoscopic Navigation:Surgical Big Data,Methodology,and Applications
随着科学技术的飞速发展,健康与环境问题日益成为人类面临的最重大问题之一。信息科学、计算机技术、电子工程与生物医学工程等学科的综合应用交叉前沿课题,研究现代工程技术方法,探索肿瘤癌症等疾病早期诊断、治疗和康复手段。本论文综述了计算机辅助微创外科手术导航、多模态医疗大数据、方法论及其临床应用:从引入微创外科手术导航概念出发,介绍了医疗大数据的术前与术中多模态医学成像方法、阐述了先进微创外科手术导航的核心流程包括计算解剖模型、术中实时导航方案、三维可视化方法及交互式软件技术,归纳了各类微创外科手术方法的临床应用。同时,重点讨论了全球各种手术导航技术在临床应用中的优缺点,分析了目前手术导航领域内的最新技术方法。在此基础上,提出了微创外科手术方法正向数字化、个性化、精准化、诊疗一体化、机器人化以及高度智能化的发展趋势。【Abstract】Interventional endoscopy (e.g., bronchoscopy, colonoscopy, laparoscopy, cystoscopy) is a widely performed procedure that involves either diagnosis of suspicious lesions or guidance for minimally invasive surgery in a variety of organs within the body cavity. Endoscopy may also be used to guide the introduction of certain items (e.g., stents) into the body. Endoscopic navigation systems seek to integrate big data with multimodal information (e.g., computed tomography, magnetic resonance images, endoscopic video sequences, ultrasound images, external trackers) relative to the patient's anatomy, control the movement of medical endoscopes and surgical tools, and guide the surgeon's actions during endoscopic interventions. Nevertheless, it remains challenging to realize the next generation of context-aware navigated endoscopy. This review presents a broad survey of various aspects of endoscopic navigation, particularly with respect to the development of endoscopic navigation techniques. First, we investigate big data with multimodal information involved in endoscopic navigation. Next, we focus on numerous methodologies used for endoscopic navigation. We then review different endoscopic procedures in clinical applications. Finally, we discuss novel techniques and promising directions for the development of endoscopic navigation.X.L. acknowledges funding from the Fundamental Research Funds for the Central Universities. T.M.P. acknowledges funding from the Canadian Foundation for Innovation, the Canadian Institutes for Health Research, the National Sciences and Engineering Research Council of Canada, and a grant from Intuitive Surgical Inc
A biomechanical approach for real-time tracking of lung tumors during External Beam Radiation Therapy (EBRT)
Lung cancer is the most common cause of cancer related death in both men and women. Radiation therapy is widely used for lung cancer treatment. However, this method can be challenging due to respiratory motion. Motion modeling is a popular method for respiratory motion compensation, while biomechanics-based motion models are believed to be more robust and accurate as they are based on the physics of motion. In this study, we aim to develop a biomechanics-based lung tumor tracking algorithm which can be used during External Beam Radiation Therapy (EBRT). An accelerated lung biomechanical model can be used during EBRT only if its boundary conditions (BCs) are defined in a way that they can be updated in real-time. As such, we have developed a lung finite element (FE) model in conjunction with a Neural Networks (NNs) based method for predicting the BCs of the lung model from chest surface motion data.
To develop the lung FE model for tumor motion prediction, thoracic 4D CT images of lung cancer patients were processed to capture the lung and diaphragm geometry, trans-pulmonary pressure, and diaphragm motion. Next, the chest surface motion was obtained through tracking the motion of the ribcage in 4D CT images. This was performed to simulate surface motion data that can be acquired using optical tracking systems. Finally, two feedforward NNs were developed, one for estimating the trans-pulmonary pressure and another for estimating the diaphragm motion from chest surface motion data.
The algorithm development consists of four steps of: 1) Automatic segmentation of the lungs and diaphragm, 2) diaphragm motion modelling using Principal Component Analysis (PCA), 3) Developing the lung FE model, and 4) Using two NNs to estimate the trans-pulmonary pressure values and diaphragm motion from chest surface motion data. The results indicate that the Dice similarity coefficient between actual and simulated tumor volumes ranges from 0.76±0.04 to 0.91±0.01, which is favorable. As such, real-time lung tumor tracking during EBRT using the proposed algorithm is feasible. Hence, further clinical studies involving lung cancer patients to assess the algorithm performance are justified
Optimization of computer-assisted intraoperative guidance for complex oncological procedures
Mención Internacional en el título de doctorThe role of technology inside the operating room is constantly increasing, allowing surgical procedures previously considered impossible or too risky due to their complexity or limited access. These reliable tools have improved surgical efficiency and safety. Cancer treatment is one of the surgical specialties that has benefited most from these techniques due to its high incidence and the accuracy required for tumor resections with conservative approaches and clear margins.
However, in many cases, introducing these technologies into surgical scenarios is expensive and entails complex setups that are obtrusive, invasive, and increase the operative time. In this thesis, we proposed convenient, accessible, reliable, and non-invasive solutions for two highly complex regions for tumor resection surgeries: pelvis and head and neck. We explored how the introduction of 3D printing, surgical navigation, and augmented reality in these scenarios provided high intraoperative precision.
First, we presented a less invasive setup for osteotomy guidance in pelvic tumor resections based on small patient-specific instruments (PSIs) fabricated with a desktop 3D printer at a low cost. We evaluated their accuracy in a cadaveric study, following a realistic workflow, and obtained similar results to previous studies with more invasive setups. We also identified the ilium as the region more prone to errors.
Then, we proposed surgical navigation using these small PSIs for image-to-patient registration. Artificial landmarks included in the PSIs substitute the anatomical landmarks and the bone surface commonly used for this step, which require additional bone exposure and is, therefore, more invasive. We also presented an alternative and more convenient installation of the dynamic reference frame used to track the patient movements in surgical navigation. The reference frame is inserted in a socket included in the PSIs and can be attached and detached without losing precision and simplifying the installation. We validated the setup in a cadaveric study, evaluating the accuracy and finding the optimal PSI configuration in the three most common scenarios for pelvic tumor resection. The results demonstrated high accuracy, where the main source of error was again incorrect placements of PSIs in regular and homogeneous regions such as the ilium.
The main limitation of PSIs is the guidance error resulting from incorrect placements. To overcome this issue, we proposed augmented reality as a tool to guide PSI installation in the patient’s bone. We developed an application for smartphones and HoloLens 2 that displays the correct position intraoperatively. We measured the placement errors in a conventional and a realistic phantom, including a silicone layer to simulate tissue. The results demonstrated a significant reduction of errors with augmented reality compared to freehand placement, ensuring an installation of the PSI close to the target area.
Finally, we proposed three setups for surgical navigation in palate tumor resections, using optical trackers and augmented reality. The tracking tools for the patient and surgical instruments were fabricated with low-cost desktop 3D printers and designed to provide less invasive setups compared to previous solutions. All setups presented similar results with high accuracy when tested in a 3D-printed patient-specific phantom. They were then validated in the real surgical case, and one of the solutions was applied for intraoperative guidance. Postoperative results demonstrated high navigation accuracy, obtaining optimal surgical outcomes. The proposed solution enabled a conservative surgical approach with a less invasive navigation setup.
To conclude, in this thesis we have proposed new setups for intraoperative navigation in two complex surgical scenarios for tumor resection. We analyzed their navigation precision, defining the optimal configurations to ensure accuracy. With this, we have demonstrated that computer-assisted surgery techniques can be integrated into the surgical workflow with accessible and non-invasive setups. These results are a step further towards optimizing the procedures and continue improving surgical outcomes in complex surgical scenarios.Programa de Doctorado en Ciencia y Tecnología Biomédica por la Universidad Carlos III de MadridPresidente: Raúl San José Estépar.- Secretario: Alba González Álvarez.- Vocal: Simon Droui
Clinical Validation of an Optical Surface Detection System for Stereotactic Radiosurgery with Frameless Immobilization Device in CNS Tumors
Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Radiações em Diagnóstico e Terapia), 2022Stereotactic Radiosurgery (SRS) has been consolidated in recent years as the treatment of
choice in selected central nervous system (CNS) tumors. With the introduction of stereotactic
approach in clinical practice, accurate immobilization and motion control during treatment becomes
fundamental. During SRS treatments, the common practice is to immobilize CNS patients in a cushion
molded head support, with specific open-face thermoplastic masks. To verify and correct internal
isocenter uncertainties before and during treatment, X-Ray volumetric imaging (XVI) is performed -
image guided radiation therapy (IGRT).
An alternative to mid‐treatment imaging is optical surface detection (OSD) imaging – a
non‐invasive, non‐radiographic form of image guidance – to monitor patient intra-fraction motion.
This imaging technique has shown to properly position, accurately monitor, and quantify patient
movements throughout the entirety of the treatment – surface guided radiation therapy (SGRT).
The aim of this investigation is to test the viability of the implementation of a maskless
immobilization approach, using only a vacuum mouthpiece suction system for head fixation in patients
with CNS tumors who will undergo SRS treatment under the guidance of an OSD system coupled with
6-Degree of Freedom (6-DOF) robotic couch for submillimeter position correction. This master thesis
addresses the five technical performance tests conducted on the Linear Accelerator components –
XVI, HexaPOD couch and OSD system in the Radiotherapy Department of Hospital CUF
Descobertas.
The results obtained lecture the best acquisition orientation to perform image verification; if
the HexaPOD couch is correctly calibrated to the XVI radiation isocenter to assure submillimeter
corrections; OSD system performance regarding phantom surface detection since some immobilization
components can block the signal reading; which coplanar and non-coplanar angles occur most signal
inconsistencies due to camera pod occlusion; what is the overall OSD system accuracy and what is the
best non-coplanar angle arrangement to perform an SRS treatment with OSD system monitoring
Advances in real-time thoracic guidance systems
Substantial tissue motion: \u3e1cm) arises in the thoracic/abdominal cavity due to respiration. There are many clinical applications in which localizing tissue with high accuracy: \u3c1mm) is important. Potential applications include radiation therapy, radio frequency ablation, lung/liver biopsies, and brachytherapy seed placement. Recent efforts have made highly accurate sub-mm 3D localization of discrete points available via electromagnetic: EM) position monitoring. Technology from Calypso Medical allows for simultaneous tracking of up to three implanted wireless transponders. Additionally, Medtronic Navigation uses wired electromagnetic tracking to guide surgical tools for image guided surgery: IGS). Utilizing real-time EM position monitoring, a prototype system was developed to guide a therapeutic linear accelerator to follow a moving target: tumor) within the lung/abdomen. In a clinical setting, electromagnetic transponders would be bronchoscopically implanted into the lung of the patient in or near the tumor. These transponders would ax to the lung tissue in a stable manner and allow real-time position knowledge throughout a course of radiation therapy. During each dose of radiation, the beam is either halted when the target is outside of a given threshold, or in a later study the beam follows the target in real-time based on the EM position monitoring. We present quantitative analysis of the accuracy and efficiency of the radiation therapy tumor tracking system. EM tracking shows promise for IGS applications. Tracking the position of the instrument tip allows for minimally invasive intervention and alleviates the trauma associated with conventional surgery. Current clinical IGS implementations are limited to static targets: e.g. craniospinal, neurological, and orthopedic intervention. We present work on the development of a respiratory correlated image guided surgery: RCIGS) system. In the RCIGS system, target positions are modeled via respiratory correlated imaging: 4DCT) coupled with a breathing surrogate representative of the patient\u27s respiratory phase/amplitude. Once the target position is known with respect to the surrogate, intervention can be performed when the target is in the correct location. The RCIGS system consists of imaging techniques and custom developed software to give visual and auditory feedback to the surgeon indicating both the proper location and time for intervention. Presented here are the details of the IGS lung system along with quantitative results of the system accuracy in motion phantom, ex-vivo porcine lung, and human cadaver environments
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