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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reconfigurable Fiducial-Integrated Modular Needle Driver For MRI-Guided Percutaneous Interventions

Ji, Wenzhi 25 April 2013 (has links)
Needle-based interventions are pervasive in Minimally Invasive Surgery (MIS), and are often used in a number of diagnostic and therapeutic procedures, including biopsy and brachytherapy seed placement. Magnetic Resonance Imaging (MRI) which can provide high quality, real time and high soft tissue contrast imaging, is an ideal guidance tool for image-guided therapy (IGT). Therefore, a MRI-guided needle-based surgical robot proves to have great potential in the application of percutaneous interventions. Presented here is the design of reconfigurable fiducial-integrated modular needle driver for MRI-guided percutaneous interventions. Further, an MRI-compatible hardware control system has been developed and enhanced to drive piezoelectric ultrasonic motors for a previously developed base robot designed to support the modular needle driver. A further contribution is the development of a fiber optic sensing system to detect robot position and joint limits. A transformer printed circuit board (PCB) and an interface board with integrated fiber optic limit sensing have been developed and tested to integrate the robot with the piezoelectric actuator control system designed by AIM Lab for closed loop control of ultrasonic Shinsei motors. A series of experiments were performed to evaluate the feasibility and accuracy of the modular needle driver. Bench top tests were conducted to validate the transformer board, fiber optic limit sensing and interface board in a lab environment. Finally, the whole robot control system was tested inside the MRI room to evaluate its MRI compatibility and stability.
2

An Automated Ultrasound Calibration Framework Incorporating Elevation Beamwidth for Tracked Ultrasound Interventions

Chen, Kuiran 22 October 2012 (has links)
Image-guided surgeries employ advanced imaging and computing technologies to assist the surgeon when direct visualization is inadequate or unavailable. As modern surgeries continue to move toward minimally invasive procedures, tracked ultrasound (US), an emerging technology that uniquely combines US imaging and position tracking, has been increasingly used for intraoperative guidance in surgical interventions. The intrinsic accuracy of a tracked US system is primarily determined by a unique procedure called ``probe calibration", where a spatial registration between the coordinate systems of the transducer (provided by a tracking device affixed to the probe) and the US image plane must be established prior to imaging. Inaccurate system calibration causes misalignments between the US image and the surgical end-effectors, which may directly contribute to treatment failure. The probe calibration quality is further reduced by the "elevation beamwidth" or "slice thickness", a unique feature of the ultrasound beam pattern that gives rise to localization errors and imaging uncertainties. In this thesis, we aim to provide an automated, pure-computation-based, intraoperative calibration solution that also incorporates the slice thickness to improve the calibration accuracy, precision and reliability. The following contributions have been made during the course of this research. First, we have designed and developed an automated, freehand US calibration system with instant feedback on its calibration accuracy. The system was able to consistently achieve submillimeter accuracy with real-time performance. Furthermore, we have developed a novel beamwidth-weighted calibration framework (USB-FW) that incorporates US slice thickness to improve the estimation of calibration parameters. The new framework provides an effective means of quality control for calibration results. Extensive phantom validation demonstrated that USB-FW introduces statistically significant reduction (p = 0.001) in the calibration errors and produces calibration outcomes that are less variable than a conventional, non-beamwidth-weighted calibration. Finally, we were the first to introduce an automated, intraoperative Transrectal Ultrasound (TRUS) calibration technology for needle guidance in prostate brachytherapy. Our tests with multiple commercial TRUS scanners and brachytherapy stepper systems demonstrated that the proposed method is practical in use and can achieve high calibration accuracy, precision and robustness. / Thesis (Ph.D, Computing) -- Queen's University, 2012-10-22 16:18:55.439
3

Synthesis of Various Classes of Cyanine Fluorophores and Their Application In In Vivo Tissue Imaging

Levitz, Andrew R 10 May 2017 (has links)
A novel series of near-infrared fluorescent contrast agents was developed and characterized. Their physicochemical and optical properties were measured. By altering functional groups of cyanine fluorophores, the selective targeting of endocrine glands, exocrine glands, cartilage and bone using NIR fluorescence to visualize the targeted tissue has been reported. These agents have high specificity for tissue targeting inherent to the chemical structure of the fluorophore. After a single low-dose intravenous injection these agents have high specificity for tissue targeting inherent to the chemical structure of the fluorophore. The results lay the foundation for future improvements in optical imaging in endocrine surgery, tissue engineering, joint surgery, and cartilage-specific drug development.
4

Design, implementation and evaluation for continuous interaction in image-guided surgery

Trevisan, Daniela 03 March 2006 (has links)
Recent progress in the overlay and registration of digital information on the users workspace in a spatially meaningful way has allowed mixed reality (MR) to become a more effective operational medium. In the area of medical surgery, surgeons are conveyed with information such as the incisions location, regions to be avoided, diseased tissues, etc, while staying in and keeping their original working environment. The main objective of this Thesis is identifying theoretical and practical basis for how mixed reality interfaces might provide support and augmentation maximizing the continuity of interaction. We start proposing a set of design principles organized in a design space which allows to identify continuity interaction properties at an early stage of the development system. Once the abstract design possibilities have been identified and a concrete design decision has been taken, an implementational strategy can be developed. Two approaches were investigated: markerless and marker-based. The last one is used to provide surgeons with guidance on an osteotomy task in the maxillo-facial surgery. The evaluation process applies usability tests with users to validate the augmented guidance in different scenarios and to study the influence of different design variables in the final user interaction. As a result we have found a model to describe the contribution factors of each variable for the continuity of the user interaction. We suggest that this methodology can be applied mainly to those applications in which smooth connections and interactions, with virtual and real environments, are critical for the system; i.e. surgery, drivers applications or pilot simulations.
5

Design, implementation and evaluation for continuous interaction in image-guided surgery

Trevisan, Daniela 03 March 2006 (has links)
Recent progress in the overlay and registration of digital information on the users workspace in a spatially meaningful way has allowed mixed reality (MR) to become a more effective operational medium. In the area of medical surgery, surgeons are conveyed with information such as the incisions location, regions to be avoided, diseased tissues, etc, while staying in and keeping their original working environment. The main objective of this Thesis is identifying theoretical and practical basis for how mixed reality interfaces might provide support and augmentation maximizing the continuity of interaction. We start proposing a set of design principles organized in a design space which allows to identify continuity interaction properties at an early stage of the development system. Once the abstract design possibilities have been identified and a concrete design decision has been taken, an implementational strategy can be developed. Two approaches were investigated: markerless and marker-based. The last one is used to provide surgeons with guidance on an osteotomy task in the maxillo-facial surgery. The evaluation process applies usability tests with users to validate the augmented guidance in different scenarios and to study the influence of different design variables in the final user interaction. As a result we have found a model to describe the contribution factors of each variable for the continuity of the user interaction. We suggest that this methodology can be applied mainly to those applications in which smooth connections and interactions, with virtual and real environments, are critical for the system; i.e. surgery, drivers applications or pilot simulations.
6

Υπολογισμός οπτικού πεδίου ενδοσκοπικής κάμερας και εφαρμογή σε σύστημα επαυξημένης πραγματικότητας για υποβοήθηση του χειρουργού

Δασκαλάκη, Αναστασία 30 May 2012 (has links)
Ο σκοπός της διπλωματικής εργασίας ήταν η ανάπτυξη ενός μοντέλου Επαυξημένης Πραγματικότητας για την υποβοήθηση του χειρουργού-χειριστή ρομποτικού μηχανήματος. Το μοντέλο αυτό παρουσιάστηκε για την εύρεση του οπτικού πεδίου του ειδικού ενδοσκοπίου. Για τον σκοπό αυτό κατασκευάστηκαν δύο προγράμματα τα οποία μπορούν να χειριστούν ιατρικά δεδομένα και να προσφέρουν εικόνες από το εσωτερικό του μοντέλου του ασθενούς. Συγκεκριμένα, έγινε μελέτη των βασικών μεθόδων εφαρμογής Επαυξημένης Πραγματικότητας στην χειρουργική, όπως η εγγραφή του ασθενούς, η κατάτμηση των ιατρικών δεδομένων, η τρισδιάστατη ανακατασκευή τους και η ανίχνευση των ενδοσκοπικών εργαλείων και της κάμερας. Παρουσιάστηκε το πλήρες θεωρητικό μοντέλο εφαρμογής επαυξημένης πραγματικότητας και έγινε ανάλυση των επιμέρους διαδικασιών. Κατασκευάστηκαν με την βοήθεια της Matlab δύο προγράμματα με τα αντίστοιχα GUIs για τον προεγχειρητικό σχεδιασμό και την διεγχειρητική καθοδήγηση/επαύξηση αντίστοιχα. Τέλος έγινε δοκιμή των προγραμμάτων χρησιμοποιώντας 22 τομές μαγνητικής τομογραφίας (μορφής DICOM) εγκεφάλου με εμφανή καρκίνο στην αριστερή κοιλία. Επίσης καταγράφηκαν οι εικόνες και τα δεδομένα που παίρνουμε σε κάθε βήμα εφαρμογής των προγραμμάτων με στόχο την αξιολόγηση τους. Το μοντέλο αυτό κατασκευάστηκε με στόχο την εφαρμογή του σε επεμβάσεις μέσω του ρομποτικού μηχανήματος daVinci. Παρόλα αυτά η γενικότερη εφαρμογή της μεθοδολογίας που αναπτύσσεται μπορεί να βρει εφαρμογές και σε άλλες ενδοσκοπικές επεμβάσεις. / The purpose of this thesis was to develop a model of Augmented Reality to assist the surgeon-operator of a robotic machine. The model has been presented for finding the field of special endoscope. For this purpose we built two programs that can manipulate medical data and provide images of the interior of the patient’s model. Specifically, a study was done in the basic methods of Augmented Reality application in Surgery such as, the registration of the patient, the segmentation of medical data, their 3D reconstruction and the detection of endoscopic instruments and the camera. Has been presented the complete theoretical model for applying augmented reality and an analysis of individual procedures was done. Moreover we constructed with the help of Matlab two programs with their GUIs, for preoperative planning and intraoperative guidance/augmentation, respectively. Finally the programs were tested, using 22 MRI slices (format DICOM) with visible brain cancer in the left ventricle. Also were recorded images and data that we get at each step of programs implementation in order to evaluate them. This model was constructed to implement the operations through the daVinci robotic machine. Nevertheless, the general application of the methodology developed in this study may find applications also in other endoscopic procedures
7

Intraoperative visualization of plasmon resonant liposomes using augmented microscopy

Watson, Jeffrey R., Garland, Summer, Romanowski, Marek 08 February 2017 (has links)
Plasmon resonance associated with nanoparticles of gold can enable photothermal ablation of tissues or controlled drug release with exquisite temporal and spatial control. These technologies may support many applications of precision medicine. However, clinical implementations of these technologies will require new methods of intraoperative imaging and guidance. Near-infrared laser surgery is a prime example that relies on improved image guidance. Here we set forth applications of augmented microscopy in guiding surgical procedures employing plasmon resonant gold-coated liposomes. Absorption of near-infrared laser light is the first step in activation of various diagnostic and therapeutic functions of these novel functional nanoparticles. Therefore, we demonstrate examples of near-infrared visualization of the laser beam and gold-coated liposomes. The augmented microscope proves to be a promisingimage guidance platform for a range of image-guided medical procedures.
8

Desvios lineares e angulares de implantes com guias prototipadas fixadas em modelos experimentais / Linear and angular deviations of implants placed with fixed stereolithographic drill guides in experimental models

Novellino, Marcelo Michele 11 August 2011 (has links)
Considerando as dificuldades que ocorrem com a localização e o posicionamento de implantes e, ainda, o risco de deslocamento das guias, tomográfica e cirúrgica, durante os procedimentos de diagnóstico e cirúrgico, foi objetivo desta pesquisa avaliar, se a alternativa de introduzir dispositivos para retenção e suporte, nas guias da técnica de cirurgia guiada convencional, interfere na posição e inclinação de implantes no momento da sua colocação. Foram confeccionados 10 modelos simulando tecido ósseo, divididos aleatoriamente em 2 grupos: 5 com a guia tomográfica e cirúrgica da técnica convencional, denominado grupo controle (M); 5 com as guias fixadas a ortoimplantes modificados associados ao sistema de encaixe o ring, representando o grupo experimental (MI). A avaliação dos resultados foi pela sobreposição dos planejamentos virtuais (Implant Viewer), derivados de tomografias computadorizadas pré-cirúrgicas, com as realizadas após a colocação dos implantes. Os resultados obtidos mostraram que não houve diferenças estatisticamente significantes para os desvios angulares (Teste Tukey F= 1,06 e p= 0, 3124) e lineares (Teste ANOVA F = 2,54 e p = 0,11). No entanto, os valores angulares individuais do grupo experimental (MI), mostraram ser mais próximos entre si, com menor variabilidade, quando comparados ao grupo controle. Concluiuse, que o uso de ortoimplantes associados ao sistema de encaixe o ring, pode trazer benefícios à técnica da cirurgia guiada convencional, reduzindo as alterações de posicionamento dos implantes no momento da sua colocação. / Computer guided surgery is an excellent alternative to the proper insertion of implants in patients with an edentulous arch or a partially edentulous area and with appropriate quantity of bone. Considering the difficulties that occur with implants placement and the risk of displacement of radiographic and surgical template during the diagnostic and surgical procedures, the aim of this research was to assess if an alternative devices for retention of radiographic and surgical templates can bring benefits for a more accurate implant placement. Ten models made by a material that simulates bone tissue were randomly divided into 2 groups: 5 with the conventional radiographic and surgical guide, which was called control group (M); 5 with modified orthodontic implants that fixed the radiographic and the surgical templates, representing the experimental group (MI). The evaluation of the results was by matching virtual plans (Implant Viewer), derived from pre-operative cone-beam CT images, with post-operative ones to calculate the deviation between planned and installed implants. The results showed that there was no statistically significant differences for angular (Tukey F = 1.06 and p = 0, 3124) and linear deviations (test ANOVA F = 2.54 and p = 0.11). However, the individual angular values of experimental group (MI) showed to be closer to each other, with lower variability when compared to control group. It was concluded that the use of modified orthodontic implant with o ring attachment can bring benefits to conventional guided surgery technique, reducing changes in ideal implant position.
9

Surgery of Low-Grade Gliomas Near Speech-Eloquent Regions: Brainmapping versus Preoperative Functional Imaging

Steinmeier, Ralf, Sobottka, Stephan B., Reiss, Gilfe, Bredow, Jan, Gerber, Johannes, Schackert, Gabriele 24 February 2014 (has links) (PDF)
The identification of eloquent areas is of utmost importance in the surgery of tumors located near speech-eloquent brain areas, since the classical concept of a constant localization was proven to be untrue and the spatial localization of these areas may show large interindividual differences. Some neurosurgical centers apply intraoperative electrophysiological methods that, however, necessitate the performance of surgery in the awake patient. This might be a severe burden both for the patient and the operating team in a procedure that lasts several hours; in addition, electrical stimulation may generate epileptic seizures. Alternatively, methods of functional brain imaging (e.g., PET, fMRI, MEG) may be applied, which allow individual localization of speech-eloquent areas. Matching of these image data with a conventional 3D-CT or MRI now allows the exact transfer of this information into the surgical field by neuronavigation. Whereas standards concerning electrophysiological stimulation techniques that could prevent a permanent postoperative worsening of language are available, until now it remains unclear whether the resection of regions shown to be active in functional brain imaging will cause a permanent postoperative deficit. / Die Identifikation sprachaktiver Areale ist von höchster Bedeutung bei der Operation von Tumoren in der Nähe des vermuteten Sprachzentrums, da das klassische Konzept einer konstanten Lokalisation des Sprachzentrums sich als unrichtig erwiesen hat und die räumliche Ausdehnung dieser Areale eine hohe interindividuelle Varianz aufweisen kann. Einige neurochirurgische Zentren benutzen deshalb intraoperativ elektrophysiologische Methoden, die jedoch eine Operation am wachen Patienten voraussetzen. Dies kann sowohl für den Patienten als auch das Operations-Team eine schwere Belastung bei diesem mehrstündigen Eingriff darstellen, zusätzlich können epileptische Anfälle durch die elektrische Stimulation generiert werden. Alternativ können Modalitäten des «functional brain imaging» (PET, fMRT, MEG usw.) eingesetzt werden, die die individuelle Lokalisation sprachaktiver Areale gestatten. Die Bildfusion dieser Daten mit einem konventionellen 3D-CT oder MRT erlaubt den exakten Transfer dieser Daten in den OP-Situs mittels Neuronavigation. Während Standards bei elektrophysiologischen Stimulationstechniken existieren, die eine permanente postoperative Verschlechterung der Sprachfunktion weitgehend verhindern, bleibt die Relevanz sprachaktiver Areale bei den neuesten bildgebenden Techniken bezüglich einer Operations-bedingten Verschlechterung der Sprachfunktion bisher noch unklar. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
10

Desvios lineares e angulares de implantes com guias prototipadas fixadas em modelos experimentais / Linear and angular deviations of implants placed with fixed stereolithographic drill guides in experimental models

Marcelo Michele Novellino 11 August 2011 (has links)
Considerando as dificuldades que ocorrem com a localização e o posicionamento de implantes e, ainda, o risco de deslocamento das guias, tomográfica e cirúrgica, durante os procedimentos de diagnóstico e cirúrgico, foi objetivo desta pesquisa avaliar, se a alternativa de introduzir dispositivos para retenção e suporte, nas guias da técnica de cirurgia guiada convencional, interfere na posição e inclinação de implantes no momento da sua colocação. Foram confeccionados 10 modelos simulando tecido ósseo, divididos aleatoriamente em 2 grupos: 5 com a guia tomográfica e cirúrgica da técnica convencional, denominado grupo controle (M); 5 com as guias fixadas a ortoimplantes modificados associados ao sistema de encaixe o ring, representando o grupo experimental (MI). A avaliação dos resultados foi pela sobreposição dos planejamentos virtuais (Implant Viewer), derivados de tomografias computadorizadas pré-cirúrgicas, com as realizadas após a colocação dos implantes. Os resultados obtidos mostraram que não houve diferenças estatisticamente significantes para os desvios angulares (Teste Tukey F= 1,06 e p= 0, 3124) e lineares (Teste ANOVA F = 2,54 e p = 0,11). No entanto, os valores angulares individuais do grupo experimental (MI), mostraram ser mais próximos entre si, com menor variabilidade, quando comparados ao grupo controle. Concluiuse, que o uso de ortoimplantes associados ao sistema de encaixe o ring, pode trazer benefícios à técnica da cirurgia guiada convencional, reduzindo as alterações de posicionamento dos implantes no momento da sua colocação. / Computer guided surgery is an excellent alternative to the proper insertion of implants in patients with an edentulous arch or a partially edentulous area and with appropriate quantity of bone. Considering the difficulties that occur with implants placement and the risk of displacement of radiographic and surgical template during the diagnostic and surgical procedures, the aim of this research was to assess if an alternative devices for retention of radiographic and surgical templates can bring benefits for a more accurate implant placement. Ten models made by a material that simulates bone tissue were randomly divided into 2 groups: 5 with the conventional radiographic and surgical guide, which was called control group (M); 5 with modified orthodontic implants that fixed the radiographic and the surgical templates, representing the experimental group (MI). The evaluation of the results was by matching virtual plans (Implant Viewer), derived from pre-operative cone-beam CT images, with post-operative ones to calculate the deviation between planned and installed implants. The results showed that there was no statistically significant differences for angular (Tukey F = 1.06 and p = 0, 3124) and linear deviations (test ANOVA F = 2.54 and p = 0.11). However, the individual angular values of experimental group (MI) showed to be closer to each other, with lower variability when compared to control group. It was concluded that the use of modified orthodontic implant with o ring attachment can bring benefits to conventional guided surgery technique, reducing changes in ideal implant position.

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