This thesis deals mainly with perfusion modeling in optical coherence tomography (OCT). The introductory part deals with basic theory of the OCT, including a description of its basic applications. Part of the work was the testing of selected contrasting materials suitable for the OCT and the design and implementation of phantoms, which were subsequently used in the main part of the thesis. In the practical part, attention is paid to the perfusion analysis in the OCT, first the application of the dilution theory in the OCT for flow estimation, then a study testing the basic theory of perfusion on OCT by means of tissue phantom. Another part of the thesis is devoted to the method of speckle variance analysis for flow visualization.

Arterial stiffness is an important biometric in predicting cardiovascular diseases, since mechanical properties serve as indicators of several pathologies such as e.g. atherosclerosis. Shear Wave Elastography (SWE) could serve as a valuable non-invasive diagnostic tool for assessing arterial stiffness, with the technique proven efficient in large homogeneous tissue. However the accuracy within arterial applications is still uncertain, following the lack of proper validation. Therefore, the aim of this study was to assess the accuracy of SWE in arterial phantoms of poly(vinyl alcohol) cryogel by developing an experimental setup with an additional mechanical testing setup as a reference method. The two setups were developed to generate identical stress states on the mounted phantoms, with a combination of axial loads and static intraluminal pressures. The acquired radiofrequency-data was analysed in the frequency domain with retrieved dispersion curves fitted to a Lamb-wave based wave propagation model. The results indicated a significant correlation between SWE and mechanical measurements for the arterial phantoms, with an average relative error of 10 % for elastic shear moduli in the range of 23 to 108 kPa. The performed accuracy quantification implies a satisfactory performance level and as well as a general feasibility of SWE in arterial vessels, indicating the potential of SWE as a future cardiovascular diagnostic tool.

Previous studies have shown an association between Pb exposure and intelligence quotient (IQ). Up until now, there is a lack of technology and methodology to assess the effects of long-term Pb exposure (such as de-myelination) in brain in-vivo. So we are developing a mouse model that will allow us to assess in vivo Pb in bone and brain structure and myelination using magnetic resonance imaging (MRI). In this project, we will discuss the feasibility of an in vivo x-ray fluorescence (XRF) system for the Pb measurement in the skeleton of whole mice. A review of literature is conducted in chapter 1. Health impacts of lead, measurement of lead, pre-existing bone Pb phantoms and mouse model selection are explained thoroughly. In chapter 2, calibration and minimum detection limits (MDLs) for the XRF measurements are documented. Calibration was performed using Plaster of Paris phantoms mimicking human bone doped with Pb concentrations ranging from 0 to 100 ppm. Detection limits for the pre-existing bone Pb phantoms were found to be 1.52 μg Pb/g plaster for 1-hour measurement. For 2 strains of Pb free mice (CD-1 and C57BL/6J), which had skull and hind facing detectors respectively, MDLs of 5.66 – 7.78 μg Pb/g and 6.69 – 8.50 μg Pb/g were determined for 3-hour measurement. This detectability of MDLs by the XRF system encourages us to proceed to measure mouse-mimicking phantoms. In order to evaluate the feasibility of a 109Cd XRF system for the Pb measurement in the skeleton of whole mice, mouse-mimicking phantoms were made and measured. The effect of variations in Pb distribution across the mouse and the applicability of the normalization in mice are discussed in chapter 3. To sum up, our system can measure Pb in whole mice in vivo at the levels of Pb in bone that are anticipated in brain de-myelination studies. Our results indicate that if multiple orientations (rotated) are measured in mice, the mean bone Pb level in whole mice will be determined accurately. / Thesis / Master of Science (MSc)

Yes / Near field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. This paper documents microwave imaging experiments on breast cancer detection, using active antenna tuning to obtain matching over a wide bandwidth. A simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and a high dielectric constant object emulating a tumor is scanned between 4 to 8 GHz with a UWB microstrip antenna. Measurements indicate that this prototype microwave sensor is a good candidate for such imaging applications. / Yorkshire Innovation Fund, Research Development Project (RDP)

No presente trabalho serão apresentadas as diretrizes e os testes necessários para a implantação de um programa de controle de qualidade para o Eclipse 7.3.10 da Varian no Hospital das Clínicas da Faculdade de Medicina da USP, de acordo com a mais recente publicação da AIEA o TRS 430. Os testes recomendados pelo TRS 430 são basicamente divididos em testes de aceitação, comissionamento (testes dosimétricos e não dosimétricos), e testes rotineiros. O documento da AIEA está sendo implementado para o Eclipse no HC para os feixes de fótons de dois aceleradores lineares da Varian, Clinac 600C e Clinac 2100C. Os testes de aceitação verificaram parâmetros de \"hardware\"; integração do sistema \"network\"; transferência de dados, e \"softwares\". Os resultados obtidos mostraram boa concordância com as especificações do fabricante. Para os testes dosimétricos de comissionamento, foram realizadas medidas de dose absoluta para diversos arranjos experimentais. Esses valores foram comparados com os valores de dose gerados pelo SPTC. A grande maioria dos testes apresentou cerca de 90% a 80% dos pontos comparados, dentro dos níveis de tolerância, ou seja, uma boa concordância entre os valores experimentais e os valores gerados pelo SPTC. Somente arranjos de campos assimétricos apresentaram discordâncias grosseiras, mostrando a necessidade de uma investigação mais apurada para esses casos. Os testes de comissionamento não dosimétricos também apresentaram resultados excelentes, com praticamente todas as ferramentas e desempenho geral do sistema de acordo com as recomendações estipuladas no TRS 430. Foram aplicados também critérios de aceitabilidade para a comparação entre os valores de UMs gerados pelo sistema e os valores de UMs calculados manualmente. Os feixes no Eclipse foram caracterizados com dados transferidos do CadPlan e com dados provenientes do recomissionamento dos aceleradores, assim sendo, para esses testes encontrou- se uma diferença de até 3% para campos conformacionados para os dados de feixe provenientes do recomissionamento dos aceleradores, e de até 4% para os dados de feixe transferidos do CadPlan, sendo que o nível de tolerância estabelecido pelo TRS 430 para o arranjo era de 3%. / This work presents the guidelines and necessary tests tom implement a quality assurance program for Eclipse 7.3.10 from Varian at Hospital das Clinicas, Sao Paulo University School of Medicine - Brazil, in accordance with the new IAEA publication TRS 430. The recommended tests for the TRS 430 air mainly classified into acceptance tests, commissioning (dosimetric and non-dosimetric tests), and routine tests. The IAEA document\'s recommendations are being implemented at the hospital for two Varian linear accelerators - Clinac 600C e Clinac 2100C. The acceptance tests verified \'hardware\', integration of network systems, data transfer and \'software\' parameters. The results obtained are in a good agreement with the manufacturer\'s specifications. Measurements of absolute dose in several set-ups were made for the commissioning dosimetric tests. These data were compared to the absolute doses determined by the TPS. The great majority of the tests showed 90% to 80% of the analyzed data in acceptance levels, with a good agreement between the experimental data and the data determined by the TPS. Only settings with asymmetric fields presented significant discords, showing the need for a more detailed inquiry for these settings. The non-dosimetric commissioning tests have also presented excellent results, with virtually all the system tools and general performance in compliance with TRS 430. The acceptance criteria have been applied for a comparison between the values of MUs generated by TPS and the calculated manually ones. The beams have been characterized for Eclipse with data transferred from CadPlan and with data from recommissioning of accelerators, so for these tests it was found a difference of at least 3% for the conformal field shape for the data originated in the beams of recommissioning and at least 4% for the data proceeded from CadPlan. The tolerance level established by TRS 430 for this setting was 3%.

No presente trabalho serão apresentadas as diretrizes e os testes necessários para a implantação de um programa de controle de qualidade para o Eclipse 7.3.10 da Varian no Hospital das Clínicas da Faculdade de Medicina da USP, de acordo com a mais recente publicação da AIEA o TRS 430. Os testes recomendados pelo TRS 430 são basicamente divididos em testes de aceitação, comissionamento (testes dosimétricos e não dosimétricos), e testes rotineiros. O documento da AIEA está sendo implementado para o Eclipse no HC para os feixes de fótons de dois aceleradores lineares da Varian, Clinac 600C e Clinac 2100C. Os testes de aceitação verificaram parâmetros de \"hardware\"; integração do sistema \"network\"; transferência de dados, e \"softwares\". Os resultados obtidos mostraram boa concordância com as especificações do fabricante. Para os testes dosimétricos de comissionamento, foram realizadas medidas de dose absoluta para diversos arranjos experimentais. Esses valores foram comparados com os valores de dose gerados pelo SPTC. A grande maioria dos testes apresentou cerca de 90% a 80% dos pontos comparados, dentro dos níveis de tolerância, ou seja, uma boa concordância entre os valores experimentais e os valores gerados pelo SPTC. Somente arranjos de campos assimétricos apresentaram discordâncias grosseiras, mostrando a necessidade de uma investigação mais apurada para esses casos. Os testes de comissionamento não dosimétricos também apresentaram resultados excelentes, com praticamente todas as ferramentas e desempenho geral do sistema de acordo com as recomendações estipuladas no TRS 430. Foram aplicados também critérios de aceitabilidade para a comparação entre os valores de UMs gerados pelo sistema e os valores de UMs calculados manualmente. Os feixes no Eclipse foram caracterizados com dados transferidos do CadPlan e com dados provenientes do recomissionamento dos aceleradores, assim sendo, para esses testes encontrou- se uma diferença de até 3% para campos conformacionados para os dados de feixe provenientes do recomissionamento dos aceleradores, e de até 4% para os dados de feixe transferidos do CadPlan, sendo que o nível de tolerância estabelecido pelo TRS 430 para o arranjo era de 3%. / This work presents the guidelines and necessary tests tom implement a quality assurance program for Eclipse 7.3.10 from Varian at Hospital das Clinicas, Sao Paulo University School of Medicine - Brazil, in accordance with the new IAEA publication TRS 430. The recommended tests for the TRS 430 air mainly classified into acceptance tests, commissioning (dosimetric and non-dosimetric tests), and routine tests. The IAEA document\'s recommendations are being implemented at the hospital for two Varian linear accelerators - Clinac 600C e Clinac 2100C. The acceptance tests verified \'hardware\', integration of network systems, data transfer and \'software\' parameters. The results obtained are in a good agreement with the manufacturer\'s specifications. Measurements of absolute dose in several set-ups were made for the commissioning dosimetric tests. These data were compared to the absolute doses determined by the TPS. The great majority of the tests showed 90% to 80% of the analyzed data in acceptance levels, with a good agreement between the experimental data and the data determined by the TPS. Only settings with asymmetric fields presented significant discords, showing the need for a more detailed inquiry for these settings. The non-dosimetric commissioning tests have also presented excellent results, with virtually all the system tools and general performance in compliance with TRS 430. The acceptance criteria have been applied for a comparison between the values of MUs generated by TPS and the calculated manually ones. The beams have been characterized for Eclipse with data transferred from CadPlan and with data from recommissioning of accelerators, so for these tests it was found a difference of at least 3% for the conformal field shape for the data originated in the beams of recommissioning and at least 4% for the data proceeded from CadPlan. The tolerance level established by TRS 430 for this setting was 3%.

L'objectif de ce travail de thèse est de développer une sonde optique dédiée à aider le neurochirurgien à parfaire la résection des glioblastomes. Ce type de tumeurs est le plus fréquent et le plus agressif. Améliorer son exérèse permettrait d’augmenter la durée de survie moyenne du patient. Une exposé des tumeurs cérébrales et de leur prise en charge médicale introduit cette thèse. Le développement comporte trois volets. En premier lieu, le dispositif expérimental et la sonde utilisée fibrée sont caractérisés. Pour ce faire, des fantômes optiques calibrés aux géométries variées ont été conçus. Après validation, ils ont permis de définir la profondeur détectée en fonction de la variation de coefficients optiques.Deuxièmement, un programme de simulation Monte-Carlo a été développé et adapté au dispositif de mesures. Grâce aux mesures sur fantômes, ce programme a été validé. Cet outil permet un gain de temps considérable dans le processus de définition des propriétés de détection d'une sonde en fonction de sa géométrie.Enfin, dans le but d'identifier des indicateurs potentiels du tissu cérébral tumoral, une campagne de mesures sur modèle animal a été menée. Une étude spectroscopique approfondie a été effectuée sur des échantillons frais ex vivo. Plusieurs indices caractéristiques des tissus tumoraux ont été mis en évidence grâce à ce travail. / This work is dedicated to the development of an optical probe, which aims at helping the neurosurgeon during glioblastoma surgery. These brain tumours are the most frequent and aggressive ones. The quality of the tumour resection is crucial for the patients’ survival.As an introduction, the different types of brain tumours are described and the way they are taken in care is explained. The manuscript is divided into three parts. First, the experimental set-up and the home-made fibre-probe are characterized, thanks to optical calibrated phantoms. The depth of detection has been determined for several optical coefficients and phantom geometries.A dedicated Monte-Carlo simulation program has been developed. Based on phantom measurements, this program has been validated. The time-consuming process of fibre probe characterisation via phantoms can be replaced by the use of the program.At last, the identification of indicators of tumourous brain tissue is studied by means of an animal model. A spectroscopic study has been performed on fresh ex-vivo rat brain slices. Several tumourous indicators have been highlighted within this study.

Les atteintes cardiovasculaires consécutives à la radiothérapie font partie des effets secondaires tardifs soulevant de nombreuses interrogations au sein de la communauté scientifique, notamment du point de vue de la relation dose-Effet et des effets concomitants d’autres facteurs de risque (chimiothérapie, cholestérol, âge, tension artérielle,…). Les coronaropathies post-Radiques sont une des principales causes de morbidité cardiaque. Cependant, l’étude des doses reçues par les coronaires lors d’une radiothérapie requiert des approximations importantes, notamment d’un point de vue morphologique. Pour les études rétrospectives avec des dossiers médicaux anciens, les informations anatomiques sont réduites à des radiographies orthogonales et quelques contours au simulateur. Pour les dossiers médicaux plus récents, l’utilisation de l’imagerie scanner pour la planification de traitement permet la considération d’une anatomie 3D, toutefois extrêmement limitée pour les coronaires en raison d’une résolution et d’un contraste trop faibles. Par ailleurs, lors de la planification de traitement des patients traités actuellement, les doses reçues par les artères coronaires sont rarement quantifiées en clinique, et quand elles le sont, c’est au moyen d’une segmentation par a priori anatomique. Ce travail de thèse propose une utilisation originale des fantômes numériques hybrides afin d’étudier les doses aux coronaires dans le cadre de radiothérapies du sein gauche et du lymphome de Hodgkin.Au cours de la thèse, une méthode d’insertion de fantômes numériques hybrides au format DICOM dans le système de planification de traitement a été développée et validée. Elle a été adaptée et testée avec des informations anatomiques limitées aux radiographies comme c’est le cas pour les dossiers médicaux anciens, pour des traitements du sein gauche.La méthode a également été adaptée pour effectuer des reconstructions dosimétriques précises aux artères coronaires de patients traités par radiothérapie pour un lymphome de Hodgkin médiastinal, ayant bénéficié d’un suivi cardiovasculaire incluant le diagnostic de sténoses coronariennes à l’aide d’un coroscanner. Par une étude cas-Témoin, le risque de sténoses à un segment d’artère coronaire donné a été évalué comme étant multiplié par 1,049 à chaque Gray aditionnel sur la dose médiane au segment d’artère coronaire.Pour les dossiers actuels, les incertitudes associées à l’approche de segmentation par a priori anatomique des artères coronaires ont été estimées dans le cadre du traitement du sein gauche, en simulant différentes topologies réalistes d’artères coronaires dans un unique thorax et en évaluant les doses, pour une balistique donnée avec et sans irradiation de la chaîne mammaire interne. La variabilité inter-Topologique de la dose moyenne à l’artère coronaire la plus irradiée, l’interventriculaire antérieure, a été estimée à respectivement 35%et 19% avec et sans irradiation de la chaîne mammaire interne tandis qu’avec la dose aux 2% du volume de l’artère interventriculaire les plus irradiés, cette variabilité est respectivement de 76% et 49%.Enfin, l’ordre de grandeur des écarts entre des mesures par films radiochromiques et des calculs de dose du système de planification de traitement ISOgray en bordure de champ et hors du champ a été évalué pour des configurations simple (fantôme physique homogène parallélépipédique, champ carré ouvert) et complexe (fantôme physique anthropomorphe avec hétérogénéités, faisceaux tangentiels rectangulaires avec filtres en coin). Ces écarts sont jugés significatifs essentiellement en bordure de champ quelle que soit la configuration. / Cardiovascular diseases following radiotherapy are major secondary late effects raising questions among the scientific community, especially regarding the dose-Effect relationship and confounding risk factors (chemotherapy, cholesterolemia, age at treatment, blood pressure,…). Post-Radiation coronary diseases are one of the main causes of cardiac morbidity. Some approximations are made when coronary doses due to radiotherapy are estimated, especially regarding the morphology. For retrospective studies with old medical records, only radiographs are usually available with sometimes some contours made with a simulator. For recent medical records, CT scans displaying the anatomy in 3D are used for radiotherapy simulation but do not allow the coronary artery visualization due to low resolution and contrast. Currently, coronary doses are barely assessed in clinical practice, and when it is done, anatomical prior knowledge is generally used. This thesis proposes an original approach based on hybrid computational phantoms to study coronary artery doses following radiotherapy for left-Side breast cancer and Hodgkin lymphoma.During the thesis, a method inserting hybrid computational phantoms in a DICOM format into the treatment planning system has been developed and validated. It has been adapted and tested in conditions where only radiographs provide anatomical information, as with old medical records for left side breast radiotherapy.The method has also been adapted to perform precise dose reconstructions to the coronary artery for patients treated for a mediastinal Hodgkin lymphoma and diagnosed with coronary stenosis through a coroscanner. A case-Control study was carried out and the risk of coronary stenosis on a coronary artery segment was assessed to be multiplied by 1.049 at each additional gray on the median dose to the coronary artery segment.For recent medical records, coronary doses uncertainties related to an approach by anatomical prior knowledge segmentation were estimated for a left side breast radiotherapy by simulating different realistic coronary artery topologies in a single representative thorax anatomy and calculating doses due to beam sets, with and without irradiation of the internal mammary chain. The inter-Topology variability of the mean dose to the most irradiated coronary artery, the left descending coronary artery, was assessed to 35% and 19% with and without the internal mammary chain irradiation, respectively; and it was of 76% and 49%, respectively, considering the dose to the most irradiated 2% of this coronary artery volume.Finally, an order of magnitude of the differences between measurments by radiochromic films and dose calculations by the ISOgray treatment planning system in the peripheral field area, has been estimated by for both a simple configuration (parallelepiped physical phantom, homogeneous media, open square field) and a complex configuration (anthropomorphic physical phantom, heterogeneous media, rectangular tangential beams with wedge filter). These differences were judged significant essentially around the geometrical border of the irradiation field for both configuration.

<p>Optical coherence tomography is an imaging modality with an outstanding resolution. During the project, a time domain OCT system based on a Michelson fibre interferometer was implemented and put into operation. A super-luminescent diode with a centre wavelength of 1295nm and a bandwidth of 45nm was selected as light source and a linear variable delay line as reference. Basic tests were made on phantoms constructed of filter foils and on gel-like agar slices with optical properties similar to human tissue. It was shown that the achievable resolution was at least 36um and can be increased. The system can easily be enhanced to create two-dimensional images.</p> / <p>Optische Kohärenztomographie ist ein bildgebendes Verfahren mit einer hervorragenden räumlichen Auflösung. Im Laufe des Projekts wurde ein OCT-System basierend auf einem faseroptischen Michelson-Interferometer implementiert und in Betrieb genommen. Als Lichtquelle wurde eine Superlumineszenzdiode mit einer Mittenwellenlänge von 1295nm und einer Bandbreite von 45nm gewählt. Eine variable optische Verzögerungsleitung diente als Referenz. Erste Messungen an Filterfolien und gelähnlichen Agarphantomen, die die optischen Eigenschaften von menschlichem Gewebe nachbildeten, lieferten eine räumliche Auflösung von mindestens 36um. Durch die modulare Bauweise ist das System leicht für zweidimensionale Aufnahmen erweiterbar.</p>

<p>To estimate the propagation of light in tissue-like optical phantoms (fat emulsions), this thesis utilized the diffuse reflectance spectroscopy in combination with Monte Carlo simulations. A method for determining the two-parametric Gegenbauer-kernal phase function was utilized in order to accurately describe the diffuse reflectance from poly-dispersive scattering optical phantoms with small source-detector separations. The method includes the spectral collimated transmission, spatially resolved diffuse reflectance spectra (SRDR) and the inverse technique of matching spectra from Monte Carlo simulations to those measured. An absolute calibration method using polystyrene micro-spheres was utilized to estimate the relation between simulated and measured SRDR intensities. The phase function parameters were comparable with previous studies and were able to model measured spectra with good accuracy. Significant differences between the phase functions for homogenized milk and the nutritive fat emulsions were found.</p><p> </p>