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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.
111

Robust multivariate analysis methods for single cell Raman spectroscopy

Kuklev, Nikita 02 September 2016 (has links)
Usefulness of a particular clinical assay is directly correlated with its ability to extract highest possible signal from available data. This is particularly relevant for personalized radiation therapy since early plan modifications confer greater benefits to treatment outcome. Recent studies have demonstrated capability of single-cell Raman microscopy to detect cellular radiation response at clinical (below 10Gy) doses, but only in certain strongly responding cell lines and after at least two day incubation. One possible cause is rather unoptimized signal processing used. This work investigates application of several advanced multivariate methods - weighted principal component analysis (WPCA), robust PCA, probabilistic PCA, and nonlinear PCA to increase radiation response signal. Representative datasets from strongly (H460 - human lung) and weakly (LNCaP - human prostate) responding cell lines were analysed in 0-50Gy and 0-10Gy dose ranges and results quantified to determine relative and absolute algorithm performance. It was found that with careful tuning, significant improvements in sensitivity and better signal separation could be achieved as compared to conventional PCA. / Graduate
112

Estudo da influência de partículas de ouro na dose absorvida em tecido mole utilizando dosimetria com gel polimérico / Study of the influence of gold particles on the absorbed dose in soft tissue using polymer gel dosimetry

Afonso, Luciana Caminha 04 October 2011 (has links)
A presença de material de alto número atômico adjacente ao tecido mole aumenta localmente a dose absorvida pelo tecido quando submetido à radiação. Este efeito ocorre devido aos fotoelétrons ejetados do material de alto número atômico. Dosímetros de gel polimérico com partículas de ouro foram utilizados para investigar este efeito. Foram realizados cálculos analíticos para estimar o aumento de dose e simulações com o método de Monte Carlo. A irradiação de amostras de gel polimérico (GP) puro e com 0,005 gAu/gGP utilizando um feixe de raios X produzido por um potencial de 150 kV filtrado com 4 mmAl e 5 mmCu resultou em uma dose absorvida pelas amostras com ouro aproximadamente 20% maior que a dose absorvida pelas amostras de gel polimérico puro. Os cálculos analíticos e a simulação com o método de Monte Carlo resultaram em um aumento de aproximadamente 30% na dose absorvida. / The presence of high-Z material adjacent to soft tissue, when submitted to irradiation, enhances locally the absorbed dose in these soft tissues. Such effect occurs due to the outscattering of photoelectrons from the high-Z material. Polymer gel dosimeters have been used to investigate this effect. Analytic calculations to estimate the dose enhancement and Monte Carlo simulations have been performed. Samples containing polymer gel (PG) with 0.005 gAu/gPG and pure polymer gel have been irradiated using an X-rays beam produced by 150 kV, filtered with 4 mm Al and 5 mm Cu, which resulted in an approximately 20% higher absorbed dose in the samples with gold in comparison to those with pure polymer gel. The analytic calculations and the Monte Carlo simulation resulted in a dose enhancement factor of approximately 30%.
113

Nanopartículas de Ouro para Radioterapia com Energia Modulada / Gold Nanoparticles for Energy Modulated Radiation Therapy

Pinto, Tatiana Marques 19 March 2013 (has links)
Nanopartículas de ouro (AuNP) compõem o estado da arte da medicina oncológica atual sendo extensivamente investigadas para aplicações em radioterapia de câncer. O acúmulo seletivo em tecidos tumorais de vascularização desordenada causa retenção aumentada das AuNP no microambiente tumoral e aumenta a permeabilidade de drogas terapêuticas por elas carreadas. A radiossensibilização observada em células em cultura tratadas com AuNP é, contudo, resultado da resposta biológica à ambos os fenômenos bioquímicos de interação com a célula alvo e físicos de interação da AuNP com a radiação ionizante. A presença do ouro metálico no citoplasma celular durante a terapia com radiação ionizante aumenta a secção de choque de absorção fotoelétrica no tecido alvo, o que contribui para o aumento potencial do dano biológico letal. Neste contexto, o objetivo principal deste trabalho é avaliar a radiossensibilização causada por nanopartículas de ouro em radioterapia em termos de parâmetros físicos e radiobiológicos. Simulação Monte Carlo com o código PENELOPE foi utilizada para estudar como a densidade de ionização local é alterada pela criação de elétrons secundários em nanopartículas de 2-100nm após interação com os feixes primários de fótons de interesse clínico de 200kV, Ir-192, Cs-137, 6MV e Co-60. O Estudo da Nanopartícula Isolada demonstrou que a densidade de ionização é fortemente aumentada com a redução da energia do feixe primário (E) de ionização, sendo, entretanto, fracamente dependente do diâmetro das AuNP. O diâmetro da AuNP (d) modula, no entanto, o espectro de elétrons secundários ejetados ao tecido-mole disposto ao redor porque modifica o número de elétrons internamente absorvidos em cada nanopartícula. Quando concentrações de ouro (!!\") entre 0,001% e 1%, são consideradas no Estudo da Célula com Nanopartículas, é possível observar que a !!\" internalizada no citoplasma aumenta a fração de reforço da densidade de ionização no tecido alvo em até 200% para baixas energias, não ultrapassando 160% para feixes de megavoltagem. A principal conclusão desta etapa é que o reforço na densidade de ionização local é resultado do balanço entre os parâmetros estudados E e !!\", e o diâmetro da AuNP, modifica o número de fotoelétrons ejetados ao meio, influenciando portanto o potencial efeito biológico. A partir dos resultados do estudo por Monte Carlo, foram desenhados os estudos radiobiológicos in vitro e in vivo com células PC3 de adnocarcionama de próstata. Nanopartículas rod shaped (AuNR) - conjugadas com Goserelin (gAuNR) princípio ativo do quimioterápico Zoladex® foram sintetizadas com sucesso para aplicações nos sistemas biológicos e nanopartículas conjugadas com polietileno glicol (pAuNR) foram utilizadas como controle biocompatível e não bioespecífico em todos os ensaios. A dinâmica de uptake celular foi estudada in vitro demostrando que a presença do biomarcador na superfície das nanopartículas aumenta a concentração efetiva de ouro internalizada nas células alvo em 5 vezes quando comparada com pAuNR. Radiossensibilização aumentada foi observada em ensaios clonogênicos, apresentando essencialmente efetividade radiobiológica relativa 27% maior para o tecido com gAuNR incorporados, quando irradiado como feixe de 6MV, 58% e 78% maior quando irradiado com os feixes de Cs137 e Ir192 respectivamente. O estudo de biodistribuição in vivo em nude mice demonstrou que as nanopartículas bioconjugadas gAuNR tem acúmulo 3 vezes maior em tumores xenográficos de próstata do que pAuNR, e o seguimento tumoral acompanhado em 55 animais demonstrou expressiva efetividade terapêutica do uso de gAuNR em Radioterapia. Foi observado !!\"#$% de 24 e 20 dias para os grupos tratados com gAuNR e pAuNR irradiados com 6MV; Este número cresce para 28 e 18 quando as irradiações são realizadas com a fonte de Braquiterapia HDR de Ir-192. Os resultados consonantes dos estudos por Monte Carlo e ensaios radiobiológicos conduzem à proposição deste trabalho à luz de sua principal conclusão: Nanopartículas de ouro bioconjugadas, gAuNR, apresentam terapêutica efetiva na Radioterapia de câncer de próstata porque modulam o espectro de elétrons no citoplasma celular causando aumento local da densidade de ionização e reforço da probabilidade de dano letal. / Gold nanoparticles (AuNP) comprise the state of the art in medical oncology being extensively investigated for applications in cancer radiation therapy. The selective accumulation in tissues with disordered vascularization increases retention of AuNP in the tumor microenvironment, what leads to enhanced permeability of conjugated drugs carried by the AuNP. The radiosensitization observed in cells treated with AuNP however is result of a combined biological response to both biochemical and physical interactions of the conjugated AuNP with ionizing radiation. The presence of metallic gold in the cell cytoplasm during radiation therapy increases the photoelectric absorption cross-section in the target tissue, thus potentially increasing the lethal biological damage. In this context, the aim of this study is to evaluate the radiosensitization caused by gold nanoparticles in radiation therapy in terms of physical and radiobiological parameters. In order to investigate the density of ionizations in cells containing AuNP, the PENELOPE Monte Carlo code was used to simulate creation of secondary electrons in nanoparticles of 2-100nm after interaction with photon beams of clinical interest: 250kV, Ir-192, Cs-137, 6MV and Co-60. The theoretical analysis was performed in two steps: the Single AuNP Study and the Cell with AuNP Study. The first study predicts that enhancing nanoparticle diameter (d) from 2-10nm keeps the density of ionization enhanced in 22-28% for all kilovoltage beams and from 38-46% for all megavoltage beams, however increasing more than 5 times the yield of electrons ejected from the AUNP to the surrounding soft-tissue when the primary beam has its energy decreased from 6MV to 250kV. In the Cell with AuNP Study, the final concentration of gold in the cytoplasm (!!\") was increased from 0.001% to 1%, showing that concentration of gold strongly modifies the density of ionization in the cell, being up to 2 and 1.6 fold for low and high energies respectively. Sequentially, conjugated AuNP were synthesized with Goserelin Acetate (gAuNR) to target PC3 prostate cancer cells, and AuNP coated with polyethylene glycol (pAuNR) were used as non-biospecific control. The radiobiological assays were following designed based on the Monte Carlo results with 6MV, Cs-137 and the Ir-192 HDR Brachytherapy source. The in vitro cellular uptake study demonstrate that the biomarker in the surface of the nanoparticles increases the effective concentration of gold in the cytoplasm by 2.4 fold compared to pAuNR. The clonogenic assays demonstrate that the relative radiobiological effectiveness is enhanced in 27%, 58% and 78% for 6MV, Cs-137 and Ir-192 respectively when cells are treated with gAuNR for 24h prior irradiation. The conjugated nanoparticles were also submitted to ICP-MS based biodistribution study that demonstrate gAuNR accumulate 3 fold in xenografts prostate tumors than pAuNR. Following these results, a tumor re-growth study in nude mice was designed considering irradiations with the 6MV and the Ir-192 HDR Brachytherapy beam energies. Nanoparticles were administrated intravenously and tumors were followed for a maximum of 30 days. Tumor delay (!!\"#$%) of 20 and 24 days were observed for groups respectively treated with gAuNR and pAuNR and the 6MV beam; And !!\"#$% of 28 and 18 days were observed for groups respectively treated with gAuNR and pAuNR and the Ir-192 HDR Brachytherapy source. Both in vitro and in vivo studies, in consonance with the Monte Carlo predictions, demonstrate that conjugated AuNP, gAuNR, improve therapeutic effectiveness for treating prostate tumors because the gold nanoparticles modulate the effective spectrum of secondary electrons in the cytoplasm, locally enhancing the density of ionizations and thus increasing probability of lethal cellular damage.
114

Modélisation, simulation et analyse numériques de l'interaction nanoparticules-rayons X : applications à la radiothérapie augmentée / Modeling, simulation and numerical analysis of the interactions between X-rays and nanoparticles : applications to the enhanced radiation therapy

Rétif, Paul 16 March 2016 (has links)
Les travaux présentés dans le cadre de cette thèse sont divisés en trois grandes parties qui concernent l’utilisation des nanoparticules métalliques pour augmenter les effets de la radiothérapie. Cette utilisation très particulière des nanoparticules n’a fait l’objet, jusqu’à présent, que d’études précliniques sauf un nano-objet qui fait actuellement l’objet de phases cliniques I et II à l’Institut Gustave Roussy de Villejuif, France. La première partie est une recherche bibliographique qui s’est concrétisée par la parution d’un état de l’art dans une revue internationale. Ce dernier identifie les paramètres jouant un rôle clef dans l’augmentation de la radiothérapie par les nanoparticules. Suite à cette étude de la littérature, le constat a été fait que la recherche préclinique en nanomédecine est plus longue et plus onéreuse que celle qui s’intéresse aux objets (macro-molécules) de taille standard. C’est pour améliorer cette prise en charge préclinique qu’une plateforme informatique de simulation Monte-Carlo des interactions nanoparticules – rayons X a été développée. Cette dernière ayant pour objectif de réaliser un classement in silico rapide et fiable des nanoparticules radiosensibilisantes permettant d’identifier de façon efficiente les nanostructures présentant les propriétés les plus prometteuses. La seconde partie de cette thèse consiste en une analyse de robustesse de ce simulateur, visant à identifier les paramètres de variabilité intrinsèques au simulateur et à quantifier leur influence sur la variation des résultats. Trois paramètres ont été identifiés comme paramètres critiques de simulation et doivent être maintenus constants entre les différentes études. Enfin, une troisième partie traite de l’application de cet outil de simulation au screening virtuel de nanoparticules radiosensilisantes. Dans cette partie sont réalisées une analyse de prédiction in silico / in vitro et une analyse de prédiction in silico / in cellulo. Les résultats très encourageants (correspondance acceptable entre les prédictions du simulateur et les résultats in cellulo) obtenus durant cette dernière phase ont également fait l’objet d’une soumission à publication dans une revue internationale. / The work that has been carried out during this PhD thesis is divided into three main parts that are related to the use of metallic nanoparticles to enhance the effects of radiation therapy. Until now, this particular use of nanoparticles has only been limited to preclinical trials apart from a single nano-object which is currently tested in phases I and II clinical trials in the Institut Gustave Roussy of Villejuif, France. The first part of this study is a bibliographic research that has been published as a review article in an international journal. The latter identifies the key parameters responsible for the enhancement of radiation therapy by nanoparticles. Following this part, the observation was made that the preclinical research in nanomedicine is longer and more expensive than for classical macromolecules. That is why, in order to improve this preclinical step, a Monte Carlo simulation platform of nanoparticles – X rays interactions has been developed. The aim of this platform is to perform a quick and reliable in silico ranking of radiosensitizing nanoparticles in order to efficiently identify the nanostructures with the most promising properties. The second part of this thesis consists of a robustness analysis of the latter simulator, aiming to identify its intrinsic variability parameters and to quantify their influence on the variability of the results. Three parameters have been identified as critical simulation parameters and should be kept constant between studies. Finally, a third part deals with the application of the simulation platform to the virtual screening of radiosensitizing nanoparticles. A predictive in silico / in vitro and in silico / in cellulo analysis are carried out in this section. Promising results (acceptable matching between simulator’s predictions and in cellulo results) obtained during this last phase were also submitted for publication in an international journal.
115

A novel method to evaluate local control of lung cancer in stereotactic body radiation therapy (SBRT) treatment using 18f-Fdg positron emission tomography (PET)

Unknown Date (has links)
An improved method is introduced for prediction of local tumor control following lung stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC) patients using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET). A normalized background-corrected tumor maximum Standard Uptake Value (SUVcmax) is introduced using the mean uptake of adjacent aorta (SUVref), instead of the maximum uptake of lung tumor (SUVmax). This method minimizes the variations associated with SUVmax and objectively demonstrates a strong correlation between the low SUVcmax (< 2.5-3.0) and local control of post lung SBRT. The false positive rates of both SUVmax and SUVcmax increase with inclusion of early (<6 months) PET scans, therefore such inclusion is not recommended for assessing local tumor control of post lung SBRT. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.
116

Dosimetric Consequences of the Parotid Glands Using CT-To-CBCT Deformable Registration During IMRT For Late Stage Head And Neck Cancers

Unknown Date (has links)
Patients receiving Intensity Modulated Radiation Therapy (IMRT) for late stage head and neck (HN) cancer often experience anatomical changes due to weight loss, tumor regression, and positional changes of normal anatomy (1). As a result, the actual dose delivered may vary from the original treatment plan. The purpose of this study was (a) to evaluate the dosimetric consequences of the parotid glands during the course of treatment, and (b) to determine if there would be an optimal timeframe for replanning. Nineteen locally advanced HN cancer patients underwent definitive IMRT. Each patient received an initial computerized tomography simulation (CT-SIM) scan and weekly cone beam computerized tomography (CBCT) scans. A Deformable Image Registration (DIR) was performed between the CT-SIM and CBCT of the parotid glands and Planning Target Volumes (PTVs) using the Eclipse treatment planning system (TPS) and the Velocity deformation software. A recalculation of the dose was performed on the weekly CBCTs using the original monitor units. The parameters for evaluation of our method were: the changes in volume of the PTVs and parotid glands, the dose coverage of the PTVs, the lateral displacement in the Center of Mass (COM), the mean dose, and Normal Tissue Complication Probability (NTCP) of the parotid glands. The studies showed a reduction of the volume in the PTVs and parotids, a medial displacement in COM, and alterations of the mean dose to the parotid glands as compared to the initial plans. Differences were observed for the dose volume coverage of the PTVs and NTCP of the parotid gland values between the initial plan and our proposed method utilizing deformable registration-based dose calculations. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
117

Learning Phantom Dose Distribution using Regression Artificial Neural Networks

Åkesson, Mattias January 2019 (has links)
Before a radiation treatment on a cancer patient can get accomplished the treatment planning system (TPS) needs to undergo a quality assurance (QA). The QA consists of a pre-treatment (PT-QA) on a synthetic phantom body. During the PT-QA, data is collected from the phantom detectors, a set of monitors (transmission detectors) and the angular state of the machine. The outcome of this thesis project is to investigate if it is possible to predict the radiation dose distribution on the phantom body based on the data from the transmission detectors and the angular state of the machine. The motive for this is that an accurate prediction model could remove the PT-QA from most of the patient treatments. Prediction difficulties lie in reducing the contaminated noise from the transmission detectors and correctly mapping the transmission data to the phantom. The task is solved by modeling an artificial neuron network (ANN), that uses a u-net architecture to reduce the noise and a novel model that maps the transmission values to the phantom based on the angular state. The results show a median relative dose deviation ~ 1%.
118

Estudos espectrais aplicados à radioterapia utilizando o método de Monte Carlo / Spectral studies applied to radiation therapy using the Monte Carlo method.

Costa, Gustavo de Menezes Pontes da 21 October 2013 (has links)
O controle da qualidade é uma prática essencial em radioterapia para se garantir que a dose prescrita seja realmente entregue ao paciente. Essa etapa da radioterapia é fundamental para o sucesso do tratamento, pois sem executá -lo o paciente pode ser subdosado ou sobredosado sem que o físico médico possa estimar o erro estabelecido entre a dose prescrita e dose recebida. Dentre os métodos para o controle da qualidade em radioterapia, as dosimetrias in vivo permitem determinar as doses recebidas pelo paciente durante o tratamento. Diferentes técnicas podem ser utilizadas em dosimetria in vivo, sendo uma das mais comuns a dosimetria por transmissão, que compreende a comparação entre os sinais de um dado dosímetro posicionado na entrada e na saída do paciente , nas condições de irradiação. Desta forma, o conhecimento dos espectros incidente e transmitido pelo paciente podem ser utilizados tanto para o cálculo das doses em profundidade no paciente quanto para a correção de resposta de dosímetros em dosimetrias in vivo por transmissão. O método Monte Carlo pode ser utilizado para reproduzir diversas situações desejadas em radioterapia, que pode ser tanto, em controle da qualidade como, em tratamentos, por ser uma ferramenta acurada e sem restrições físicas e financeiras. Esse trabalho se propõe a determinar a perturbação sofrida pelo feixe primário ao atravessar objetos simuladores por meio da determinação da fluência energética e da energia depositada em diferentes condições de irradiação, através do método Monte Carlo. Neste trabalho foi desenvolvida uma quantidade de situações utilizando-se o código PENELOPE para possibilitar a análise do comportamento de fluências energéticas e energias depositadas. Os parâmetros clínicos que sofreram variação para a analise foram a espessura do objeto simulador, o tamanho de campo e a distância fonte-superfície (DFS). Os resultados deste trabalho mostram que a dependência em relação a cada parâmetro clínico é diferente, como é o caso da DFS, que influência mais na resposta do que o tamanho de campo, por exemplo. Portanto, esse trabalho pode ser uma ferramenta para trabalhos posteriores no estabelecimento de protocolos de relação entre fluência e dose, bem como, de armazenamento ou aplicação de dose em pacientes. / Quality control is an essential practice in radiation oncology in order to ensure that the prescribed dose is delivered to the patient. This step of radiation therapy is very important to successful treatment, because without it the patient may receive bellow dose or over dose without the physical doctor can estimate the error established between the prescribed dose and dose received. One of the methods for quality control in radiotherapy, the in vivo dosimetry let you determine the doses received by the patient during the treatment. Different techniques can be used in vivo dosimetry, being one of the most common dosimetry for transmission, which includes the comparison of the signs of a dosimeter placed on the entrance and exit of patient irradiation conditions. In this way, the knowledge of incident spectra and transmitted by the patient can be used for both the calculation of doses in depth in the patient as to the dosimeter response in vivo dosimetry for transmission. The Monte Carlo method can be used to make a variety of situations you want in radiotherapy, and may be as much in quality as in control treatments for being a tool accurately and without physical and financial constraints. This work aims to determine the disturbance suffered by primary beam across objects simulators through determination of energy flow and energy deposited in different irradiation conditions through the Monte Carlo method. This work was developed a number of situations using the PENELOPE code to enable the analysis of the behavior of energy deposited energies and skills. The clinical parameters that have suffered the assess variation ranges were the thickness of the object Simulator, the field size and source surface distance (SSD). The results show that the dependence on each clinical parameter is different, as is the case of DFS, which most influence on response than the field size, for example. Therefore, this work can be a tool for further work on the establishment of relationship between fluency and protocols, as well as dose, dose storage in patients.
119

Estudo da influência de partículas de ouro na dose absorvida em tecido mole utilizando dosimetria com gel polimérico / Study of the influence of gold particles on the absorbed dose in soft tissue using polymer gel dosimetry

Luciana Caminha Afonso 04 October 2011 (has links)
A presença de material de alto número atômico adjacente ao tecido mole aumenta localmente a dose absorvida pelo tecido quando submetido à radiação. Este efeito ocorre devido aos fotoelétrons ejetados do material de alto número atômico. Dosímetros de gel polimérico com partículas de ouro foram utilizados para investigar este efeito. Foram realizados cálculos analíticos para estimar o aumento de dose e simulações com o método de Monte Carlo. A irradiação de amostras de gel polimérico (GP) puro e com 0,005 gAu/gGP utilizando um feixe de raios X produzido por um potencial de 150 kV filtrado com 4 mmAl e 5 mmCu resultou em uma dose absorvida pelas amostras com ouro aproximadamente 20% maior que a dose absorvida pelas amostras de gel polimérico puro. Os cálculos analíticos e a simulação com o método de Monte Carlo resultaram em um aumento de aproximadamente 30% na dose absorvida. / The presence of high-Z material adjacent to soft tissue, when submitted to irradiation, enhances locally the absorbed dose in these soft tissues. Such effect occurs due to the outscattering of photoelectrons from the high-Z material. Polymer gel dosimeters have been used to investigate this effect. Analytic calculations to estimate the dose enhancement and Monte Carlo simulations have been performed. Samples containing polymer gel (PG) with 0.005 gAu/gPG and pure polymer gel have been irradiated using an X-rays beam produced by 150 kV, filtered with 4 mm Al and 5 mm Cu, which resulted in an approximately 20% higher absorbed dose in the samples with gold in comparison to those with pure polymer gel. The analytic calculations and the Monte Carlo simulation resulted in a dose enhancement factor of approximately 30%.
120

Caracterização de dosímetros semicondutores e suas aplicações em técnicas especializadas em radioterapia / Characterization of Semiconductors Dosimeters and their Applications in Specialized Techniques in Radiation Therapy.

Oliveira, Fernanda Ferretti de 21 December 2012 (has links)
Introdução: A Radioterapia é frequentemente utilizada no tratamento do câncer, seja como uma modalidade simples ou em combinação com outras modalidades, tais como a cirurgia e a quimioterapia. Com o objetivo de eliminar células não desejadas no organismo humano, utiliza-se de radiações ionizantes para provocar a destruição de células tumorais pela absorção da energia da radiação incidente. A principal dificuldade encontrada em radioterapia é que as células tumorais não são tratadas isoladamente, isto é, o dano da radiação não é restrito somente às células tumorais, mas afeta também as células normais. Assim sendo, é essencial que a dose de radiação liberada nos tecidos normais seja tão baixa quanto possível para minimizar o risco de efeitos colaterais provocados pelos tratamentos radioterápicos. Objetivos: O objetivo deste trabalho é a caracterização de dosímetros semicondutores e dosímetros termoluminescentes e suas aplicações em técnicas não convencionais de Radioterapia. A partir da caracterização será possível a implementação dos dosímetros como sistema de dosimetria in vivo em teleterapia com feixe de fótons, visando atender as necessidades prementes do Serviço de Radioterapia do HCFMRP em implantar a técnica de irradiação de corpo inteiro e em realizar o controle de dose administrada ao paciente. Metodologia e Resultados: Diodos semicondutores foram caracterizados de acordo com o fator campo, angulação, taxa de dose, temperatura e fator bandeja, para obtenção dos fatores de correção. Verificou-se que a variação da resposta dos diodos com a temperatura, angulação e taxa de dose não foi significativa. Fatores campo foram calculados e registrados para campos de 3x3 cm 2 a 40x40cm 2 , onde se observou aumento na leitura do diodo com o aumento no campo. A resposta com a taxa de dose apr esentou pouca variação (de 100cGy/min para 300cGy/min a variação foi menor que 1,2%). O fator bandeja encontrado foi de 0,95±0,01 demonstrando que a presença da bandeja provoca diminuição na resposta do detector. Após a caracterização, os diodos foram calibrados em setup TBI para determinação dos fatores de calibração para cada espessura simulada do paciente (DLL). A dosimetria in vivo foi realizada em 3 pacientes submetidos ao tratamento de TBI do HCFMRP. A diferença percentual máxima entre as medidas com diodo e o valor nominal de dose foi de 3,6%, o que está de acordo com o recomendado pelo ICRU (+/- 5%). Os resultados demonstram a viabilidade e confiabilidade da técnica de dosimetria com diodos semicondutores para Controle de Qualidade de dose em tratamento de TBI. Ainda, dosímetros termoluminescentes foram caracterizados quanto à homogeneidade do grupo e a linearidade. Os fatores de calibração individuais foram encontrados e os dosímetros foram aplicados em simulações em setup TBI. Os cálculos de dose das simulações realizadas com os termoluminescentes inseridos nos orifícios de um OSA demonstraram concordância com os valores nominais de dose. Para as regiões do tórax superior e inferior, onde os TLD receberam doses mais elevadas (>150cGy), recomendou-se a utilização de compensadores de dose, para a prática clínica.Uma câmara de ionização foi utilizada como dosímetro de referência em todas as etapas de calibração e caracterização dos diodos e termoluminescentes. Conclusões: Este estudo mostrou que, para tratamentos de irradiação de corpo inteiro, quando o paciente estiver sendo preparado para um transplante de medula óssea, e o planejamento necessitar de uma grande eficácia na distribuição de dose, a metodologia com aplicações de dosímetros semicondutores apresenta-se como uma alternativa viável, precisa e de grande importância para o controle dosimétrico. Assim, ficou evidenciada a importância da utilização do diodo para o Controle de Qualidade, na avaliação da dos e a ser ministrada ao paciente, pelo menos em toda primeira fração de tratamento de TBI. Além disso, ficou demonstrada a aplicabilidade dos dosímetros termoluminescentes para controle dosimétrico, demonstrando o valor da dosimetria termoluminescente como um sistema de verificação de dose e sua eficácia como parte de um programa de garantia de qualidade em Radioterapia. A caracterização dos termoluminescentes evidenciou a possibilidade de aplicação da técnica TL em dosimetria in vivo. / Introduction: Radiation therapy is often used in cancer treatment, either as a single modality or in combination with other modalities, such as surgery and chemotherapy. Aiming to eliminate unwanted cells in the human body, radiation therapy uses ionizing radiation to cause destruction of tumor cells by absorbing the energy of the incident radiation. The main difficulty in radiation therapy is that tumor cells are not separately treated. The radiation damage is not restricted solely to tumor cells, but also affects normal cells. Therefore, it is essential that the radiation dose released in normal tissues is as low as possible to minimize the risk of side effects caused by radiotherapy treatments. Objectives: The objective of this work is the characterization of semiconductor dosimeters and thermoluminescent dosimeters and their applications in non -conventional radiotherapy techniques. After characterization it will be possible to implement the dosimeters as a system of in vivo dosimetry in radiotherapy with photon beam, to meet the pressing needs of the Radiotherapy Service of HCFMRP in deploying the technique of total body irradiation and make the control of dose administered to the patient . Methodology and Results: Semiconductor diodes were characterized according to the field factor, angle, dose rate, temperature and tray factor to obtain the correction factors. It was found that the variation of the response of the diodes with temperature, angle and dose rate was not significant. Field factors were calculated and recorded for fields from 3x3 cm 2 to 40x40cm 2 , wher e there was an increase in the reading of the diode with increasing field. The response with dose rate showed small variation (from 100cGy/min to 300cGy/min the variation was less than 1.2%). The tray factor was 0.95 ± 0.01 demonstrating that the tray decreases detector response. After characterization, the diodes were calibrated in TBI setup for determining the calibration factors for each simulated patient thickness (latero-lateral distance). The in vivo dosimetry was performed in 3 patients undergoing TBI treatment in HCFMRP. The maximum percentage difference between the measurements and the diode nominal dose was 3.6%, which is consistent with that recommended by ICRU (+ / - 5%). The results demonstrate the feasibility and reliability of the dosimetry technique with semiconductor diodes for dose quality control in TBI treatments. Still, dosimeters were characterized by group homogeneity and linearity. The calibration factors were found and individual dosimeters were applied in simulations with TBI setup. The dose calculation of simulations performed with the thermoluminescent inserted in holes of the phantom showed agreement with the nominal dose. For regions of the upper and lower thorax where TLD received higher doses (> 150cGy) it was recommended the use of compensating dose in clinic. An ionization chamber dosimeter was used as reference in all stages of calibration and characterization of diodes and thermoluminescents. Conclusions: This study showed that, for total body irradiation treatments, when the patient is being prepared for a bone marrow transplant, and planning requires a great effect on the dose distribution, the methodology with semiconductor dosimeters presented a viable alternative, and has great importance for the dosimetric control. The study proved the importance of diode semiconductors for quality control, for evaluation of the dose to be administered to the patient, at least throughout the first fraction of TBI treating. Furthermore, it was demonstrated the applicability of TLD for control quality, demonstrating the value of thermoluminescent dosimetry as a dose verification system and its effectiveness as part of a program of quality assurance in radiotherapy. The characterization of thermoluminescent showed the possibility of applying the TL technique in in vivo dosimetry.

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