Modern image guided radiation therapy involves the use of an isocentrically mounted imaging system to take radiographs of a patient's position before the start of each treatment. Image guidance helps to minimize errors associated with a patients setup, but the radiation dose received by patients from imaging must be managed to ensure no additional risks. The Varian On-Board Imager (OBI) (Varian Medical Systems, Inc., Palo Alto, CA) does not have an automatic exposure control system and therefore requires exposure factors to be manually selected. Without patient specific exposure factors, images may become saturated and require multiple unnecessary exposures. A software based automatic exposure control system has been developed to predict optimal, patient specific exposure factors. The OBI system was modelled in terms of the x-ray tube output and detector response in order to calculate the level of detector saturation for any exposure situation. Digitally reconstructed radiographs are produced via ray-tracing through the patients' volumetric datasets that are acquired for treatment planning. The ray-trace determines the attenuation of the patient and subsequent x-ray spectra incident on the imaging detector. The resulting spectra are used in the detector response model to determine the exposure levels required to minimize detector saturation. Images calculated for various phantoms showed good agreement with the images that were acquired on the OBI. Overall, regions of detector saturation were accurately predicted and the detector response for non-saturated regions in images of an anthropomorphic phantom were calculated to generally be within 5 to 10 % of the measured values. Calculations were performed on patient data and found similar results as the phantom images, with the calculated images being able to determine detector saturation with close agreement to images that were acquired during treatment. Overall, it was shown that the system model and calculation method could potentially be used to predict patients' exposure factors before their treatment begins, thus preventing the need for multiple exposures. / Graduate / 0760 / 0574 / 0756

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.

L’imagerie de fluorescence est une technique d’imagerie médicale permettant de visualiser l’émission d’un traceur, ou fluorophore, à l’aide d’une excitation de type Laser ou LED. Les domaines d’application de la technologie sont la chirurgie oncologique, la chirurgie reconstructive ou encore la chirurgie cardiaque. Bien que les besoins en chirurgie ouverte soient importants, l’évolution des pratiques tend à démocratiser la chirurgie dite minimalement invasive. La chirurgie endoscopique va dans ce sens, le but étant de limiter les traumatismes opératoires rencontrés en chirurgie ouverte. Parmi les avantages de cette techniques on note une diminution des saignements et de la douleur, ou encore une réduction de la durée d’hospitalisation.Lors d’une intervention de type chirurgie ouverte, le praticien peur se contenter de la seuls information de fluorescence fournie par le système d’imagerie. Cependant, tout l’enjeu de l’imagerie de fluorescence pour la chirurgie mini-invasive est de venir greffer ne information relative au fluorophore sur une image couleur de très bonne qualité, essentielle au chirurgien. Pour une première évaluation, un système deux caméras a été réalisé. Un capteur est dédié à l’acquisition de l’image couleur et un autre à l’information de fluorescence. Cependant, notamment pour conserver pour conserver un système compact et proposer la meilleure ergonomie possible au chirurgien, l’endoscope final ne devra comporter qu’un seul imageur. Le principe de base est d’utiliser des impulsions de lumière d’excitation et de lumière blanche afin de séquentiellement acquérir les données de fluorescence et les images couleur. Il convient ensuite de traiter les informations recueillies pour reconstruire l’image désirée en temps réel. / Fluorescence image-guided surgery is a medical imaging modality which allows the surgeon to visualize a fluorescent probe previously injected to the patient. The probe could be specific or not and the technology is useful in a wide range of application from oncologic procedures to reconstructive surgeries or cardiac procedures. Despite the important needs of this technology in open-procedures, the surgery in general is more and more minimally invasive. The goal of mini-invasive surgery is to limit patient's per and post operation trauma. The advantages of the technique are a decrease of bleeding and pain and a decreasing hospitalization time.During an open surgery, the B&W fluorescence information given by the fluorescence image-guided surgery system is enough for the surgeon. For mini-invasive procedures, the in-game is to overlay the fluorescence information to high quality color image, compulsory for the surgeon to perform his procedure. As a first evaluation, a 2-sensors system has been rapidly developed. One sensor is dedicated to the acquisition of the color image and the other to the fluorescence information. In order to make the system more compact and improve the quality of the color image furnished to the surgeon, the final system should be composed of only one sensor. To create the color image and collect the fluorescence information with one sensor, the technique involved pulsed white light and excitation light in a sequential acquisition mode. The two information are combined and a real-time color plus fluorescence video is displayed to the surgeon.

<p>Proton beam therapy has shown great promise for cancer treatment due to its high precision in irradiating tumor volumes. However, due to the massive size and expense of the cyclotrons/synchrotrons needed to accelerate the protons, the widespread use of proton therapy is limited. Laser plasma accelerated (LPA) proton beams may be a potential alternative to conventional proton beams: by shooting an ultraintense, ultrashort pulsed laser at a thin target, a plasma sheath electric field may be formed with the capability of accelerating protons to potentially therapeutic energies in very short distances. In addition to accessibility, there is significant uncertainty in proton range in heterogeneous tissues. Thermoacoustic computed tomographic (TACT) imaging has the potential to provide <em>in vivo</em> dose imaging and range verification to address these uncertainties. TACT measures thermoacoustic waves generated from the absorbed dose and implements a 3D filtered backprojection to reconstruct volumetric images of the dose. The purpose of this thesis is to determine the feasibility of integrating LPA proton beams with thermoacoustic imaging into a novel image-guided small animal therapy platform as an early step towards clinical  translation to address the issues of accessibility and dosimetric spatial uncertainty. A Monte Carlo (MC) method is used to simulate an LPA proton beam with characteristics based on literature, thermoacoustic waves are simulated on a voxel-wise basis of the MC dose, and 3D filtered backprojection is used to reconstruct a volumetric image of the dose. In Specific Aim 1, the dependence of image accuracy on transducer array angular coverage is investigated; in Specific Aim 2, an iterative reconstruction algorithm is implemented to improve image accuracy through increased sampling of projection space when transducer array angular coverage is insufficient; and in Specific Aim 3, the detector sensitivity to dose is determined for several therapeutic endpoints. The work presented in this thesis not only demonstrates the feasibility of integrating LPA and thermoacoustic technologies but necessary design changes to realize a functional small animal platform.</p>

In the past twenty years, the combination of the advances in medical imaging technologies and therapeutic methods had a great impact in developing minimally invasive interventional procedures. Although the use of medical imaging for the surgery and therapy guidance dates back to the early days of x-ray discovery, there is an increasing evidence in using the new imaging modalities such as computed tomography (CT), magnetic reso- nance imaging (MRI) and ultrasound in the operating rooms. The focus of this thesis is on developing image-guided interventional methods and techniques to support the radiation therapy treatment of gynecologic cancers. Gynecologic cancers which involves malignan- cies of the uterus, cervix, vagina and the ovaries are one of the top causes of mortality and morbidity among the women in U.S. and worldwide. The common treatment plan for radiation therapy of gynecologic cancers is chemotherapy and external beam radiation therapy followed by brachytherapy. Gynecological brachytherapy involves placement of interstitial catheters in and around the tumor area, often with the aid of an applicator. The goal is to create an optimal brachytherapy treatment plan that leads to maximal radiation dose to the cancerous tissue and minimal destructive radiation to the organs at risk. The accuracy of the catheter placement has a leading effect in the success of the treatment. However there are several techniques are developed for navigation of catheters and needles for procedures such as prostate biopsy, brain biopsy, and cardiac ablation, it is obviously lacking for gynecologic brachytherapy procedures. This thesis proposes a technique which aims to increase the accuracy and efficiency of catheter placements in gynecologic brachytherapy by guiding the catheters with an electromagnetic tracking system. To increase the accuracy of needle placement a navigation system has been set up and the appropriate software tools were developed and released for the public use as a module in the open-source 3D Slicer software. The developed technology can be translated from benchmark to the bedside to offer the potential benefit of maximizing tumor coverage during catheter placement while avoiding damage to the adjacent organs including bladder, rectum and bowel. To test the designed system two independent experiments were designed and performed on a phantom model in order to evaluate the targeting accuracy of the tracking system and the mean targeting error over all experiments was less than 2.9 mm, which can be compared to the targeting errors in the available commercial clinical navigation systems.

Image guidance is a common methodology of minimally invasive procedures. Depending on the type of intervention, various imaging modalities are available. Common imaging modalities are computed tomography, magnetic resonance tomography, and ultrasound. Robotic systems have been developed to enable and improve the procedures using these imaging techniques. Spatial and technological constraints limit the development of versatile robotic systems. This paper offers a brief overview of the developments of robotic systems for image-guided interventions since 2015 and includes samples of our current research in this field.

The percutaneous biopsy is a critical intervention for diagnosis and staging in cancer therapy. Robotic systems can improve the efficiency and outcome of such procedures while alleviating stress for physicians and patients. However, the high complexity of operation and the limited possibilities for robotic integration in the operating room (OR) decrease user acceptance and the number of deployed robots. Collaborative systems and standardized device communication may provide approaches to overcome named problems. Derived from the IEEE 11073 SDC standard terminology of medical device systems, we designed and validated a medical robotic device system (MERODES) to access and control a collaborative setup of two KUKA robots for ultrasound-guided needle insertions. The system is based on a novel standard for service-oriented device connectivity and utilizes collaborative principles to enhance user experience. Implementing separated workflow applications allows for a flexible system setup and configuration. The system was validated in three separate test scenarios to measure accuracies for 1) co-registration, 2) needle target planning in a water bath and 3) in an abdominal phantom. The co-registration accuracy averaged 0.94 ± 0.42 mm. The positioning errors ranged from 0.86 ± 0.42 to 1.19 ± 0.70 mm in the water bath setup and from 1.69 ± 0.92 to 1.96 ± 0.86 mm in the phantom. The presented results serve as a proof-of-concept and add to the current state of the art to alleviate system deployment and fast configuration for percutaneous robotic interventions.

Ce travail de thèse porte sur la quantification et la prise en compte des variations anatomiques en cours de radiothérapie guidée par l'image pour le cancer de la prostate. Nous proposons tout d'abord une approche basée population pour quantifier et analyser les incertitudes géométriques, notamment à travers des matrices de probabilité de présence de la cible en cours de traitement. Nous proposons ensuite une méthode d'optimisation des marges suivant des critères de couverture géométrique de la cible tumorale. Cette méthode permet d'obtenir des marges objectives associées aux différents types d'incertitudes géométriques et aux différentes modalités de repositionnement du patient. Dans un second temps, nous proposons une méthode d'estimation de la dose cumulée reçue localement par les tissus pendant un traitement de radiothérapie de la prostate. Cette méthode repose notamment sur une étape de recalage d'images de façon à estimer les déformations des organes entre les séances de traitement et la planification. Différentes méthodes de recalage sont proposées, suivant les informations disponibles (délinéations ou points homologues) pour contraindre la déformation estimée. De façon à évaluer les méthodes proposées au regard de l'objectif de cumul de dose, nous proposons ensuite la génération et l'utilisation d'un fantôme numérique reposant sur un modèle biomécanique des organes considérés. Les résultats de l'approche sont présentés sur ce fantôme numérique et sur données réelles. Nous montrons ainsi que l'apport de contraintes géométriques permet d'améliorer significativement la précision du cumul et que la méthode reposant sur la sélection de contraintes ponctuelles présente un bon compromis entre niveau d'interaction et précision du résultat. Enfin, nous abordons la question de l'analyse de données de populations de patients dans le but de mieux comprendre les relations entre dose délivrée localement et effets cliniques. Grâce au recalage déformable d'une population de patients sur une référence anatomique, les régions dont la dose est significativement liée aux événements de récidive sont identifiées. Il s'agit d'une étude exploratoire visant à terme à mieux exploiter l'information portée par l'intégralité de la distribution de dose, et ce en fonction du profil du cancer. / This work deals with the quantification and the compensation of anatomical deformations during image-guided radiotherapy of prostate cancer. Firstly, we propose a population-based approach to quantify the geometrical uncertainties by means of coverage probability matrices of the target tumor during the treatment. We then propose a margins optimization method based on geometrical coverage criteria of the tumor target. This method provides rationnal margins models associated to the different geometrical uncertainties and patient repositioning protocols. Secondly, we propose a method to estimate the locally accumulated dose during the treatment. This method relies on a deformable image registration process in order to estimate the organ deformations between each treatment fraction and the planning. Different registration methods are proposed, using different level of user interactions (landmarks specification or delineations) to constrain the deformation estimation. In order to evaluate the performance of the proposed methods, we then describe the generation of a numerical phantom based on a biomechanical model. The results are presented for the numerical phantom and real clinical cases. We show that the benefit brought by the manual placement of some landmarks to constrain the registration represents a good compromise between the required interaction level and the dose estimation accuracy. Finally, we address the issue of the analysis of population data in order to better understand the relationship between the locally delivered dose and clinical effects. With deformable image registration of a population of patients on an anatomical template, regions whose dose is significantly associated with recurrence events are identified. This last part is an exploratory study aiming to better use the information carried by the entire distribution dose, and according to the cancer profile.

Monte Carlo (MC) and Pencil Beam (PB) calculations are compared to their measured planar dose distributions using a 2-D diode array for lung Stereotactic Body Radiation Therapy (SBRT). The planar dose distributions were studied for two different phantom types: an in-house heterogeneous phantom and a homogeneous phantom. The motivation is to mimic the human anatomy during a lung SBRT treatment and incorporate heterogeneities into the pre-treatment Quality Assurance process, where measured and calculated planar dose distributions are compared before the radiation treatment. Individual and combined field dosimetry has been performed for both fixed gantry angle (anterior to posterior) and planned gantry angle delivery. A gamma analysis has been performed for all beam arrangements. The measurements were obtained using the 2-D diode array MapCHECK 2™. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Introdução e objetivo: A avaliação da gravidade da neoplasia em pacientes com câncer de próstata tem como propósito identificar e tratar somente os pacientes com doença clinicamente significativa. Os parâmetros clínicos e histopatológicos tradicionalmente utilizados na estratificação de risco classificam erroneamente uma parcela importante dos pacientes. O objetivo deste estudo foi avaliar o papel da ressonância nuclear multiparamétrica de próstata (RNMMP) e da biópsia transretal realizada com fusão de imagem e estimativa visual na estratificação precoce dos pacientes em vigilância ativa. Métodos: Foram incluídos prospectivamente pacientes com câncer de próstata de baixo risco candidatos a vigilância ativa: biópsia inicial convencional com no mínimo 12 fragmentos; escore de Gleason <= 6; PSA sérico <= 10,0; <= 3 fragmentos positivos; <= 50% de acometimento de cada fragmento; toque T1c ou T2a. Todos os pacientes foram submetidos à RNMMP e biópsia confirmatória: biópsia aleatória sistemática e biópsia guiada com fusão de imagem (ultrassom e RNMMP) e analisada por método cognitivo de estimativa visual. As regiões suspeitas para câncer foram definidas e classificadas utilizando-se a escala PI-RADS (Prostate Imaging Reporting and Data System). Definimos reclassificação na biópsia confirmatória como aparecimento de escore de Gleason >= 7, > 3 fragmentos positivos ou >= 50% de envolvimento de qualquer fragmento. A performance da RNMMP em prever os resultados da biópsia confirmatória foi estudada. Análise uni e multivariada mediante regressão logística avaliou a relação entre idade, PSA, densidade de PSA, número de fragmentos positivos na biópsia inicial e o escore da RNMMP e a chance de reclassificação na biópsia confirmatória. Resultados: Cento e cinco pacientes estiveram disponíveis para análise final. Quarenta e dois (40%) pacientes apresentaram PI-RADS 1,2 ou 3 e 63 (60%) PI-RADS 4 ou 5. No geral, 87 pacientes foram submetidos à biópsia guiada com fusão. A taxa de reclassificação entre pacientes com PI-RADS 1,2,3,4 e 5 foi de 0%, 23.1%, 9.1%, 74.5% e 100%, respectivamente. No geral, a sensibilidade, especificidade, valor preditivo positivo (VPP) e valor preditivos negativo (VPN) da RNMMP para predição de reclassificação foi de 92.5%, 76%, 81% e 90.5%, respectivamente. Daqueles reclassificados, 47 (44.8%) tinham escore de Gleason >= 7 e 11 apresentavam (10.4%) >= 3 fragmentos positivos e >= 50% de envolvimento de qualquer fragmento individualmente. Na análise multivariada, somente a densidade de PSA e a RNMMP permaneceram como fatores preditivos significativos para reclassificação (p < 0,05). Na tabulação cruzada a biópsia aleatória sistemática teria deixado de classificar corretamente 15 pacientes com câncer significativo detectados pela biópsia com fusão de imagem. Por outro lado, a biópsia aleatória sistemática detectou cinco casos de câncer significante que não teriam sido identificados pela biopsia de fusão de imagem isoladamente. Conclusões: A RNMMP é uma ferramenta importante na predição da taxa de reclassificação da gravidade da neoplasia de próstata em pacientes candidatos à vigilância ativa submetidos à biopsia confirmatória. A taxa de reclassificação na biopsia confirmatória é particularmente alta no grupo de pacientes com lesões PI-RADS grau 4-5. Apesar da utilidade da biópsia com fusão de imagem, recomenda-se a manutenção da prática de se retirar fragmentos sistemáticos aleatórios quando da realização da biópsia confirmatória para maximizar a detecção de neoplasia de comportamento agressivo / Introduction and objective: The goal of prostate cancer (PCa) risk stratification is to identify and treat only men with clinically significant disease. Clinical and pathologic parameters currently used to stratify PCa risk misclassify a significant amount of patients. The objective of this study was to evaluate the role of multiparametric magnetic resonance imaging of the prostate (mpMRI) and transrectal guided biopsy with visual estimation (TRUS-Bx) in early risk stratification of patients with prostate cancer on active surveillance. Methods: Study subjects were prospectively enrolled including patients with low risk, low-grade, localized PCa: Gleason <= 6, T1c-T2a, PSA <=10 ng/ml, no more than 3 positive cores and <= 50% involvement of single cores. They were followed with subsequent mp-MRI and confirmatory biopsy (CB): standard biopsy (SB) and visual estimation-guided TRUS-Bx. Cancer-suspicious regions (CSRs) were defined using Prostate Imaging Reporting And Data System (PIRADS) scores. Reclassification occurred if CB confirmed Gleason >= 7, > 3 positive fragments or >= 50% involvement of any core. The performance of mp- MRI on predicting CB results was assessed. Univariate and multivariate logistic regression were performed to study relationships between age, PSA, PSA density, number of positive cores in the initial biopsy and mpMRI grade on CB reclassification. Results: 105 patients were available for analysis. 42 (40%) patients had PIRADS 1,2 or 3 lesions and 63 (60%) had only grades 4 or 5 lesions. Overall, 87 patients underwent visual estimation TRUS-Bx. Reclassification among patients with PI-RADS 1,2,3,4 and 5 was 0%, 23.1%, 9.1%, 74.5% and 100%, respectively. Overall, mpMRI sensitivity, specificity, PPV and NPV for disease reclassification were 92.5%, 76%, 81% and 90.5%, respectively. Of men reclassified 47 (44.8%) were upstaged because of Gleason >= 7, 11 (10.4%) because of >= 3 positive fragments plus >= 50% involvement. On multivariate analysis, only PSA density and mpMRI remained significant for reclassification (p < 0,05). On cross-tabulation SB would have missed 15 significant cases detected by targeted biopsy. On the other hand SB detected 5 cases of significant cancer not detected by targeted biopsy alone. Conclusions: Multiparametric magnetic resonance imaging is a significant tool for predicting cancer severity reclassification on CBx among AS candidates. The reclassification rate on CBx is particularly high in the group of patients who have PI-RADS grades 4 or 5 lesions. Despite the usefulness of visual-guided biopsy, it still remains highly recommended to retrieve standard fragments during CBx in order to avoid missing significant tumors