Dissertations / Theses on the topic 'Radiotherapy and Nuclear Medicine'
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COSTA, ALESSANDRO M. da. "Metodos de calibracao e de intercomparacao de calibradores de dose utilizados em servicos de medicina nuclear." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10713.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Massicano, Felipe. "Modelagem de um sistema de planejamento em radioterapia e medicina nuclear com o uso do código MCNP6." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-11032016-093447/.
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O tratamento de câncer possui diversas modalidades. Uma delas é a utilização de fontes de radiação como principal protagonista do tratamento. A radioterapia e a medicina nuclear são exemplos desse tipo de tratamento. Por utilizarem a radiação ionizante como principal ferramenta para a terapia, há a necessidade de se efetuar diversas simulações do tratamento a fim de maximizar a dose nos tecidos tumorais sem ultrapassar os limites de dose nos tecidos sadios circunvizinhos. Os sistemas utilizados na simulação desses tipos de terapia recebem o nome de Sistemas de Planejamento Dosimétrico. A medicina nuclear e a radioterapia possuem seus próprios sistemas de planejamento dosimétricos devido a grande diversidade das informações necessárias às suas simulações. Os sistemas de planejamento em radioterapia são mais consolidados do que os de medicina nuclear e por tal motivo um sistema que aborde tanto os casos de radioterapia como de medicina nuclear contribuiria para significativos avanços na área de medicina nuclear. Dessa forma, o objetivo do trabalho foi modelar um Sistema de Planejamento Dosimétrico com o uso do código de Monte Carlo MCNP6 Monte Carlo N-Particle Transport Code que permitisse incorporar os casos de radioterapia e medicina nuclear e que fosse extensível a novos tipos de tratamentos. A modelagem desse sistema resultou na construção de um Framework, orientado a objetos, nomeado IBMC o qual auxilia no desenvolvimento de sistemas de planejamento que necessitam interpretar grandes quantidades de informações com o objetivo de escrever o arquivo base do MCNP6. O IBMC permitiu desenvolver de maneira rápida e prática sistemas de planejamento para radioterapia e medicina nuclear e os resultados foram validados com sistemas já consolidados. Ele também mostrou alto potencial para desenvolver sistemas de planejamento de novos tipos de tratamentos que utilizam a radiação ionizante.Cancer therapy has many branches and one of them is the use of radiation sources as treatment leading method. Radiotherapy and nuclear medicine are examples of these treatment types. For using the ionization radiation as main tool for the therapy, there is the need of crafting many treatment simulation in order to maximum the tumoral tissue dose without throught the dose limit in health tissue surrounding. Treatment planning systems (TPS) are systems which have the purpose of simulating these therapy types. Nuclear medicine and radiotherapy have many distinct features linked to the therapy mode and consequently they have different TPS destined for each. The radiotherapy TPS is more developed than the nuclear medicine TPS and by that reason the development of a TPS that was similar to the radiotherapy TPS, but enough generic for include other therapy types, it will contribute with significant advances in nuclear medicine and in others therapy types with radiation. Based on this, the goal of work was to model a TPS that utilizes the Monte Carlo N-Particle Transport code (MCNP6) in order to simulate radiotherapy therapy, nuclear medicine therapy and with potential for simulating other therapy types too. The result of this work was the creation of a Framework in Java language, objectoriented, named IBMC which will assist in the development of new TPS with MCNP6 code. The IBMC allowed to develop rapidly and easily TPS for radiotherapy and nuclear medicine and the results were validated with systems already consolidated. The IBMC showed high potential for developing TPS by new therapy types.
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Adjeiwaah, Mary. "Quality assurance for magnetic resonance imaging (MRI) in radiotherapy." Licentiate thesis, Umeå universitet, Institutionen för strålningsvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-142603.
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Magnetic resonance imaging (MRI) utilizes the magnetic properties of tissues to generate image-forming signals. MRI has exquisite soft-tissue contrast and since tumors are mainly soft-tissues, it offers improved delineation of the target volume and nearby organs at risk. The proposed Magnetic Resonance-only Radiotherapy (MR-only RT) work flow allows for the use of MRI as the sole imaging modality in the radiotherapy (RT) treatment planning of cancer. There are, however, issues with geometric distortions inherent with MR image acquisition processes. These distortions result from imperfections in the main magnetic field, nonlinear gradients, as well as field disturbances introduced by the imaged object. In this thesis, we quantified the effect of system related and patient-induced susceptibility geometric distortions on dose distributions for prostate as well as head and neck cancers. Methods to mitigate these distortions were also studied. In Study I, mean worst system related residual distortions of 3.19, 2.52 and 2.08 mm at bandwidths (BW) of 122, 244 and 488 Hz/pixel up to a radial distance of 25 cm from a 3T PET/MR scanner was measured with a large field of view (FoV) phantom. Subsequently, we estimated maximum shifts of 5.8, 2.9 and 1.5 mm due to patient-induced susceptibility distortions. VMAT-optimized treatment plans initially performed on distorted CT (dCT) images and recalculated on real CT datasets resulted in a dose difference of less than 0.5%. The magnetic susceptibility differences at tissue-metallic,-air and -bone interfaces result in local B0 magnetic field inhomogeneities. The distortion shifts caused by these field inhomogeneities can be reduced by shimming. Study II aimed to investigate the use of shimming to improve the homogeneity of local B0 magnetic field which will be beneficial for radiotherapy applications. A shimming simulation based on spherical harmonics modeling was developed. The spinal cord, an organ at risk is surrounded by bone and in close proximity to the lungs may have high susceptibility differences. In this region, mean pixel shifts caused by local B0 field inhomogeneities were reduced from 3.47±1.22 mm to 1.35±0.44 mm and 0.99±0.30 mm using first and second order shimming respectively. This was for a bandwidth of 122 Hz/pixel and an in-plane voxel size of 1×1 mm2. Also examined in Study II as in Study I was the dosimetric effect of geometric distortions on 21 Head and Neck cancer treatment plans. The dose difference in D50 at the PTV between distorted CT and real CT plans was less than 1.0%. In conclusion, the effect of MR geometric distortions on dose plans was small. Generally, we found patient-induced susceptibility distortions were larger compared with residual system distortions at all delineated structures except the external contour. This information will be relevant when setting margins for treatment volumes and organs at risk. The current practice of characterizing MR geometric distortions utilizing spatial accuracy phantoms alone may not be enough for an MR-only radiotherapy workflow. Therefore, measures to mitigate patient-induced susceptibility effects in clinical practice such as patient-specific correction algorithms are needed to complement existing distortion reduction methods such as high acquisition bandwidth and shimming.
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MASSICANO, FELIPE. "Modelagem de um sistema de planejamento em radioterapia e medicina nuclear com o uso do código MCNP6." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26371.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Shortkroff, Sonya. "The influence of radionuclides on synovitis and its assessment by MRI." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326039.
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COSTA, ALESSANDRO M. da. "Desenvolvimento de camaras de ionizacao Tandem para utilizacao em programas de controle da qualidade em radioterapia e radiodiagnostico." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11103.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:98/14763-4
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Vouche, Michael. "Radiation Segmentectomy, Radiation Lobectomy and Response Assessment after 90Yttrium Radioembolization for Hepatocellular carcinoma: Imaging and Clinical Implications." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/241979.
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Hepatocellular carcinoma is a primary liver cancer.Among treatment options for hepatocellular carcinoma, Yttrium-90 radioembolization is a promising transarterial therapy.This thesis investigates potential clinical applications of radioembolization in the treatment of the hepatocellular carcinoma (techniques of radiation segmentectomy and radiation lobectomy), and adress the problematic of the response Assessment after radioembolization.Doctorat en Sciences médicales (Médecine)
info:eu-repo/semantics/nonPublished
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Costa, Gustavo. "IRDose : un outil web de dosimétrie individualisée basé sur la méthode Monte Carlo pour les patients en thérapie avec le 177Lu." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30027.
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La médecine nucléaire est une spécialité médicale qui utilise un radiopharmaceutique dont l'administration permet généralement de visualiser une fonction, en détectant les émissions gamma (γ) du radio-isotope vectorisé. Lorsque le but de cette pratique est la thérapie (radiothérapie moléculaire), on privilégie des isotopes qui émettent des radiation à courte portée (α, β ou électrons Auger). Les traitements utilisant 177Lu-DOTATATE ont obtenu leur autorisation de mise sur le marché (AMM) sur la base de l'administration de 7,4 GBq par cycle (activité fixe), sans tenir compte de la variabilité de fixation inter patient. Ceci entraîne une importante fluctuation de la dose absorbée délivrée aux organes à risque et aux cibles tumorales, et par conséquent, une grande difficulté à prédire les résultats du traitement. Des études récentes suggèrent que la planification basée sur une dosimétrie individuelle est une piste d'optimisation du traitement. L'objectif de ce travail est de participer au développement de la dosimétrie clinique en radiothérapie moléculaire, notamment par le développement d'un outil web dédié à la dosimétrie interne personnalisée de patients traités avec 177Lu et basé sur la méthode Monte-Carlo. Dans un premier temps, nous avons réalisé une étude sur la modélisation de systèmes SPECT avec le code Monte-Carlo GATE. L'optimisation des simulations a été réalisée par différentes méthodes pour réduire les temps de simulation. Ces techniques ont réduit le temps de simulation jusqu'à un facteur de 85. Certaines ont été utilisées dans la comparaison entre acquisitions tomographiques simulées et expérimentales. Cette comparaison a permis la modélisation du contexte expérimental utilisé dans la validation de l'outil web, Finalement, une page web a été conçue en utilisant le framework Django où une séquence de scripts en Python et Bash réalisent le calcul de la dose absorbée par simulation avec GATE. Les doses absorbée obtenues ont été comparées avec OLINDA (version 1 et 2). Nos résultats montrent des différences entre 0,3% et 6,1%, selon la version d'OLINDANuclear medicine is a medical specialty that uses a radiopharmaceutical whose administration generally allows to visualize an organ function by detecting the gamma (γ) emissions of the targeted radioisotope. When the goal of this practice is molecular radiotherapy, isotopes emitting short-range radiation (α, β or electron Augers) are preferred. In general, treatments using 177Lu-DOTATATE still uses the historical practice of a fixed administration of 7.4 GBq per cycle, regardless the sex, age or inter-patient fixation variability. This causes a large fluctuation of the absorbed dose delivered to organs at risk and tumour targets, and therefore a great difficulty in predicting the treatment results. Recent studies suggest that treatment planning based on individual dosimetry is a way to optimize the treatment. The objective of this work is to contribute to the development of clinical dosimetry in molecular radiotherapy, in particular by developing a web tool based on the Monte Carlo method GATE dedicated to individualised internal dosimetry of patients treated with 177Lu. First of all, a study on the modelling of the SPECT systems by the Monte Carlo toolkit, GATE was realized, as well as the optimization of these simulations, where different methods were used in order to reduce simulation time. These techniques reduced simulation time by up to 85, and some of them were used in the comparison between simulated and experimental tomographic acquisitions. This comparison allowed the modelling of an experimental context which was used for the web tool validation. Finally, the web page was designed using the Django framework where a sequence of scripts in Python and Bash perform the calculation of the absorbed dose by GATE simulations. The absorbed doses obtained were compared with OLINDA versions 1 and 2, and the results show differences between 0.3% and 6.1%, depending on OLINDA's version
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MARTINS, ELAINE W. "Desenvolvimento e aplicação de um simulador pediátrico craniano para dosimetria em tomografia computadorizada." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26608.
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Para avaliar os níveis de exposição e a dose absorvida em pacientes submetidos a exames de tomografia computadorizada, TC, é necessário calcular os índices de dose em medições com um simulador de PMMA, ou cheio de água. O simulador deve ser capaz de reproduzir as características de absorção e espalhamento do corpo ou parte do corpo humano em um campo de radiação. As grandezas específicas em TC: índice de kerma livre no ar (Ca,100), índice de kerma no ar ponderado (CW), índice de kerma no volume total (Cvol) e produto kerma no ar-comprimento (PKL) devem ser determinadas e comparadas com os níveis de referência já existentes na literatura. Neste trabalho foi desenvolvido um simulador pediátrico craniano, já que no Brasil os níveis de referência para diagnósticos (NRDs) disponíveis foram determinados baseados em um simulador padrão adulto. O simulador desenvolvido inovou em sua construção apresentando materiais que simulam a calota craniana em osso cortical (alumínio) e osso esponjoso (PVC). O seu interior foi preenchido com água destilada. As dimensões foram escolhidas de acordo com as recomendações da Organização Mundial da Saúde e do International Commission on Radiation Units, para o tamanho da cabeça de uma criança de 0 a 5 anos: 160 mm de diâmetro e 155 mm de altura. A calota craniana tem uma espessura de 4 mm e diâmetro interno de 111,9 mm. Para avaliar seu comportamento foram realizados testes em laboratórios e em feixes clínicos. Os resultados apresentaram uma atenuação de até 23% na utilização dos materiais que simulam a calota craniana evidenciando que os valores adotados para os cálculos de NRD podem estar superestimando a dose recebida por pacientes pediátricos. Percebe-se que a dose recebida em exames de crânio apresenta uma distribuição diferente por ser parcialmente atenuada e/ou retroespalhada pela calota craniana, o que não é considerado ao se utilizar o simulador constituído apenas de PMMA.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Sjögren, Adam. "The impact of metallic cranial implants on proton-beam radiotherapy treatment plans for near implant located tumours : A phantom study on the physical effects and agreement between simulated treatment plans and the resulting treatment for near implant located cranial tumours." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149530.
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Within the field of radiotherapy treatments of tumour diseases, the hunt for more accurate and effective treatment methods is a continuous process. For some years ion-beam based radiotherapy, especially the proton-beam based applications, has increased in popularity and availability. The main reason behind this is the fact that ion-beam based applications make it possible to modulate the dose after the planning target volume (PTV) defined by the radiation oncologist. This means that it becomes possible to spare tissue in another way, which might result in more effective treatments, especially in the vicinity of radio sensitive organs. Ion-beam based treatments are however more sensitive to uncertainties in PTV position and beam range as ion-beams have a fixed range depending on target media and initial energy, as opposed to the conventional x-ray beams that do not really have a defined range. Instead their intensity decreases exponentially at a rate dependent of the initial energy and target media. Therefore density heterogeneities result in uncertainties in the planned treatments. As the plans normally are created using a CT-images, for which metallic implants can yield increased heterogeneities both from the implants themselves and so called metal artifacts (distortions in the images caused by different processes as the X-rays used in image acquisition goes through metals). Metallic implants affects the accuracy of a treatment, and therefore also the related risks, so it is important to have an idea of the magnitude of the impact. Therefore the aim of this study is to estimate the impact on a proton-beam based treatment plan for six cranial implants. These were one Ti-mesh implant, one temporal plate implant, one burr-hole cover implant and three craniofix implants of different sizes, which all are commonly seen at the Skandion clinic. Also the ability of the treatment planning system (TPS), used at the clinic, to simulate the effects on the plans caused by the implants is to be studied. From this result it should be estimated if the margins and practices in place at the clinic, for when it is required to aim the beam through the implant, are sufficient or if they should be changed. This study consisted of one test on the range shift effects and one test on the lateral dose distribution changes, with one preparational test in the form of a calibration of Gafchromic EBT3 films. The range shift test was performed on three of the implants, excluding the three craniofix implants using a water phantom and a treatment plan created to represent a standard treatment in the cranial area. The lateral dose distribution change test was performed as a solid phantom study using radiochromic film, for two treatment plans (one where the PTV was located \SI{2}{\centi\metre} below surface, for all implants, and one where it was located at the surface, only for the Ti-mesh and the temporal plate). The results of both tests were compared to simulations performed in the Eclipse treatment planing system (TPS) available at Skandion. The result of the range shift test showed a maximum range shift of \SI{-1.03 +- 0.01}{\milli\metre}, for the burr-hole cover implant, and as the related Eclipse simulations showed a maximal shift of \SI{-0.17 +- 0.01}{\milli\metre} there was a clear problem with the simulation. However, this might not be because of the TPS but due to errors in the CT-image reconstruction, such as, for example, geometrical errors in the representation of the implants. As the margin applied for a similar situation at the Skandion clinic (in order to correct for several uncertainty factors) is \SI{4.2}{\milli\metre} there might be a need to increase this margin depending on the situation. For the lateral distribution effects no definite results were found as the change varied in magnitude, even if it tended to manifest as a decreasing dose for the first plan and a increasing dose for the second. It was therefore concluded that further studies are needed before anything clear can be said.
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Mairs, Robert J. "Targeted radiotherapy of cancer." Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248190.
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Murphy, Caroline Claire Scanlon. "A history of radiotherapy to 1950 : cancer and radiotherapy in Britain 1850-1950." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278710.
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Millin, Anthony. "Verification of stereotactic radiotherapy." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/12287/.
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Investigations have been made into the use of a computer based simulation technique (Monte Carlo (MC)) to ionising radiation transport in order to verify the doses delivered during linear accelerator based stereotactic radiotherapy and radiosurgery. Due to the complex nature of the micro multi-leaf collimators (μMLC) used in this these treatments, a bespoke model of the μMLC was developed and combined with standard component modules to represent the remainder of the linear accelerator. Following validation of the above models, investigations were made into the dosimetry of small fields, defined by the μMLC and measured with a variety of detectors. Comparisons of relative output, profiles and depth doses were made against MC simulations, and a series of correction factors determined, to account for detector geometry and the non water equivalence of materials used in semiconductor detectors. An assessment was then made to determine the smallest fields that can be measured with each detector with confidence. Systems were then developed to independently simulate stereotactic treatments and compare doses simulated with those calculated by the treatment planning system (TPS); excellent agreement between TPS calculations and MC simulations was observed. The application of MC methods to determine the most appropriate treatment tactics and calculation algorithms for stereotactic body radiotherapy in the lung was then investigated with recommendations made on the most appropriate calculation algorithms and beam arrangements for the technique. The doses calculated using the type-b or collapsed cone algorithm agreed most closely with the MC simulation. There was little difference observed between plans using more than four beams in the treatment delivery. Treatment techniques using only three beams or less achieved poorer coverage of the tumour with dose, producing lower doses at the periphery of the tumour near the interface with the surrounding lung tissue, compared to using a greater number of beams. Finally, methods of transit dosimetry using Electronic Portal Imaging Devices were investigated for use in cranial stereotactic radiotherapy. Three methods were investigated based on a full MC simulation of the radiation transport through the patient and on to the imager, prediction of the dose based on a TPS calculation and an approximation of the radiological path length of the central axis of the beams to derive an expected dose at the imager plane. The MC method produced the best agreement at the expense of a longer time to acquire the comparison doses compared to the TPS calculation method. The equivalent path length method showed good agreement (within 3.5%) between delivered and predicted doses but at a single point.
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Scaife, Lucy. "Proteomic identification of putative biomarkers of radiotherapy resistance." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:6870.
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Background Currently, tumour response to radiotherapy cannot be predicted meaning that those patients with tumours resistant to the therapy endure the harmful side effects associated with ionising radiation in the absence of therapeutic gain. The aim of this project was to identify protein biomarkers predictive of radiotherapy response using comparative proteomic platforms to study radioresistant cell line models. The identification of such biomarkers will enable radiotherapy to be tailored on an individual patient basis and hence increase treatment efficacy. Methods Seven radioresistant (RR) cell line models derived from breast, head and neck (oral), and rectal cancers were investigated to identify differentially expressed proteins (DEPs) associated with radiotherapy resistance. This included the establishment of 2 RR rectal cancer cell line models and the proteomic analysis of 2 RR oral cancer cell lines and 2 RR rectal cancer cell lines. Proteomic analysis included 3 different platforms, namely antibody microarray, 2D MS and iTRAQ. Data mining of all biomarker discovery data, from all 7 novel RR cell lines was carried out using Ingenuity Pathway Analysis (IPA) which identified canonical pathways associated with the data. Protein candidates from selected canonical pathways were confirmed by western blotting and assessed clinically using immunohistochemistry. Results Following the combination of all biomarker discovery data for all 7 RR cell lines, 373 unique DEPs were successfully mapped onto the Ingenuity Knowledge Base, generating 339 canonical pathways. Of these, 13 of the most relevant pathways were selected for further interpretation. Several proteasomal subunits were identified during the biomarker discovery phase and were mapped onto the protein ubiquitination pathway by IPA. DR4, was identified in 4/7 RR cell lines and was mapped onto the death receptor signalling pathway by IPA. Radiotherapy is typically thought to induce cellular apoptosis via the intrinsic (mitochondrial) pathway, therefore the repeated identification of the DR4 protein involved in the extrinsic apoptotic pathway has potentially lead to the discovery of a novel relationship between radiotherapy and the extrinsic death receptor pathway. The differential expression of both the 26S Proteasome and DR4 were confirmed by western blotting. Clinical assessment using immunohistochemistry revealed a significant association between expression of the 26S Proteasome and radioresistance in breast cancer. Discussion A large number of DEPs which may be associated with radiotherapy resistance in breast, oral and rectal cancers have been identified using comparative proteomic platforms. The protein ubiquitination pathway and the death receptor signalling pathway may play a significant role in radioresistance and proteins within these pathways may be putative biomarkers of radiotherapy response.
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Book, Lynn Novella. "Surface imaging for patient setup and monitoring for breast radiotherapy." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41311.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 66-67).
Approximately one in eight women will get breast cancer at some point in their lives. A promising new treatment is partial breast irradiation, in which multiple radiation beams cross at the tumor site within the patient. This method of radiotherapy treats only a portion of the breast for a relatively small number of treatments with a high dose per treatment. This method requires much higher accuracy of patient alignment as the tumor site must be correct targeted. This study examined the possibility of using the VisionRT (London, UK) software and cameras for surface visualization to align patients for this treatment. A portable, single pod, the "Mini Cam" was found to be able to generate images for translations less than 2.5-5.5 cm, depending on the direction of translation. Calibration was a key aspect to ensuring accurate results. Eight patients were studied for deformation, breathing motion and day to day alignment. Surface images were taken at several points during regular treatment. Deformation was found to be small and never exceeded and average value of 2 mm. No correlation was found between the amount of deformation and the breast size or planning treatment volume. The average peak-to-peak breathing motion was 0.99-2.16 mm. Variability was discovered in the gating function of the VisionRT software. Aligning patients based on the first treatment session was found to be more accurate than aligning to a CT image taken weeks earlier.
by Lynn Novella Book.
S.M.
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Davidson, Susan Elizabeth. "Potential prognostic indicators for the radiotherapy of cervical carcinoma." Thesis, University College London (University of London), 1991. http://discovery.ucl.ac.uk/1348985/.
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Biopsies from 117 patients with proven cervical carcinoma were taken under anaesthesia immediately prior to radiotherapy. The Courtenay Mills soft agar clonogenic assay was used to determine the colony forming efficiency (CFE) of tumour cells from disaggregated tumours and the survival of these cells following radiation. Validation of the assay was carried out by demonstrating linearity of colony formation and production of radiation survival curves. The mean CFE was 0.18±0.49% (±lsd) with a range of 0.003 - 4.28% (based on total viable nucleated cell counts) for 84 (72%) specimens. No significant association was demonstrated between in vitro growth and either clinical stage (r=0.02) or tumour differentiation (r=0.08). A wide range of values (0.13-0.97) for surviving fraction at 2Gy (SF2) was obtained with a mean value 0.44 (sd=0.19) for 77 tumours. There were statistically significant differences between the individual tumours (p=<. 001). Heterogeneity in intrinsic radiosensitivity was not demonstrated (p=0.3) when multiple biopsies were processed independently from 18 tumours. From analysis of variance of the SF2 results it appears that the surviving fraction below 0.4 and those above 0.7 which show significant differences in radiosensitivity between pairs of tumours (p=OO5). Differential cell counts were made on cytospin preparations of tumour cell suspensions. There was no correlation between either CFE or SF2 (r = -0.05, r=0.15, respectively) and the degree of lymphocyte (r = 0.12) or macrophage (r = 0.001) infiltration. Ki67 staining of 29 specimens gave a mean proportion of positively stained nuclei of 20.5% (sd=23). The Ki67 index was not correlated with tumour stage (r=0.58), differentiation (r=0.02), CFE (r=0.04) or SF2 (r="0.07). Vascularity was assessed on paraffin sections of 87 tumours. The mean intercapillary distance (ICD) was 240μm (sd=37pm) and mean proportion of vessels was 2.68% (sd=1.64%). Clinical data from 35 patients with 2 year minimum follow-up revealed no significant difference between the mean ICD or mean proportion of vessels for the group of patients which had died or recurred and the group which remained disease free using t-tests (t=0.74, p=0.47, DF=32; t= 0.6, p=0.55, DF=29 respectively).
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Obeidat, Mohammad Ali. "Radiotherapy Measurements with a Deoxyribonucleic Acid Doublestrand-Break Dosimeter." Thesis, The University of Texas Health Science Center at San Antonio, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10281552.
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Many types of dosimeters are used in the clinic to measure radiation dose for therapy but none of them directly measures the biological effect of this dose. The overall purpose of this work was to develop a dosimeter that measures biological damage in the form of double-strand breaks to deoxyribonucleic acid. This dosimeter could provide a more biologically relevant measure of radiation damage than the currently utilized dosimeters. A pair of oligonucleotides was designed to fabricate this dosimeter. One is labeled with a 5’-end biotin and the other with a 5’-end 6 Fluorescein amidite (fluorescent dye excited at 495?nanometer, with a peak emission at 520 nanometer). These were designed to adhere to certain locations on the pRS316 vector and serve as the primers for polymerase chain reactions. The end product of this reaction is a 4 kilo-base pair double strands deoxyribonucleic acid fragment with biotin on one end and 6 Fluorescein amidite oligonucleotide on the other attached to streptavidin beads. The biotin end connects the double strands deoxyribonucleic acid to the streptavidin bead. These bead-connected double strands deoxyribonucleic acid were suspended in 50 microliter of phosphate-buffered saline and placed into a tube for irradiation. Following irradiation of the deoxyribonucleic acid dosimeter, we take advantage of the magnetic properties of the streptavidin bead by placing our sample microtube against a magnet. The magnetic field pulls the streptavidin beads against the side of the tube. If a double-strand-break has occurred for a double strands deoxyribonucleic acid, the fluorescein end of the double strands deoxyribonucleic acid becomes free and is no longer attached to the bead or held against the side of the microtube. The free fluorescein following a double-strand-break in double strands deoxyribonucleic acid is referred to here as supernatant. The supernatant is extracted and placed in another microtube, while the unbroken double strands deoxyribonucleic acid remain attached to the beads and stay in the microtube (Fig. 4). Those beads were re-suspended with 50 microliter of phosphate-buffered saline again (called beads), then we placed both supernatant and beads in a reader microplate and we read the fluorescence signal for both with a fluorescence reader (BioTek Synergy 2). These beads and supernatant fluorescence signals are denoted by B and S, respectively. The relative amount of supernatant fluorescence counts is proportional to the probability of a double-strand-break. The probability of double-strand-break was calculated with the following equation:
(S-BG)/(S+B-2BG) (1)
where S was the supernatant fluorescence intensity (related to the number of double strands deoxyribonucleic acid with double-strand breaks), B was the re-suspended beads fluorescence intensity (related to the number of double strands deoxyribonucleic acid without double-strand breaks), and BG was the phosphate-buffered saline fluorescence intensity (related to the background signal). There are two advantages that this type of dosimeter has over the gel separation technique. First, it is important to irradiate deoxyribonucleic acid in a solution that has similar osmolarity and ion concentrations to that in a human, such as phosphate-buffered saline. A gel dosimeter would require a transfer to gel to separate deoxyribonucleic acid, whereas our dosimeter can be separated in this solution. Currently, we use pipettes to manually perform this separation, but this step could be automated. Second, the magnetic deoxyribonucleic acid separation technique is much faster than that for gel electrophoresis. Calibration of radiotherapy equipment isn’t something that happens in national science laboratories, with only world-leading experts. This is something that happens locally at every cancer clinic, with physicists that do not have the luxury of focusing solely on this one measurement. For this reason, ease of use is critical for this type of technology. (Abstract shortened by ProQuest.)
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Cufflin, Rebecca Sian. "Verification of Intensity Modulated Radiotherapy." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/25873/.
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The main aim of this work was to develop accurate and efficient methods for the verification of Intensity Modulated Radiotherapy (IMRT). IMRT is an advanced form of radiotherapy demanding extensive verification procedures to ensure treatments are delivered accurately. This requires comprehensive sampling of the complex dose distributions impacting on the tumour volume and radiationsensitive ‘organs at risk’. This work has focused on the use of electronic portal imaging devices (EPIDs) for verification purposes. Modern EPIDs are composed of a scintillator and an amorphous silicon detector panel with an array of photodiodes and thin film transistors. They are primarily used to verify the patient position during treatment by capturing transmission images, but they also have the potential to be used as efficient dose verification tools of high spatial resolution. Two complementary dose verification methods have been developed. One approach involves the calculation of portal dose using Monte Carlo (MC) methods. A MC model of the linear accelerator, in combination with the EPID, enables the dose to the detector to be predicted accurately and compared directly with acquired images. An alternative approach has also been developed. This utilises a clinical treatment planning system (TPS) to calculate the dose at the detector level, and convert this to predicted EPID intensity by application of a series of derived correction factors. Additionally, there have been numerous publications in the literature detailing problems in dosimetry caused by non-uniform backscatter to the imager from the model of detector support arm used in this work. Two novel methods to correct for this issue have been developed, a MC modelling solution and a matrix-based correction. These developed methods for IMRT dose verification have been applied both prior to and during treatment. When applied to pre-treatment verification, the MC solution is accurate to the 2%, 2 mm level (an average of 96% of points passing gamma criteria of 2%, 2 mm) and the TPS based method is accurate to the 3%, 3 mm level (an average of 98% of points passing gamma criteria of 3%, 3 mm). Both verification methods achieve acceptable verification results during treatment at the 5%, 5 mm level (average gamma pass rates of 97% and 96% being achieved for the MC and TPS based solutions respectively). Furthermore, in initial clinical studies, both techniques have identified dose delivery errors due to changes in patient position or patient anatomy.
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Sooriyajeevan, M. J. S. J. "Image filtering in nuclear medicine." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU090122.
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Nuclear medicine images are degraded by blurring caused by the gamma camera system response function and the inherent Poisson noise of radioactivity. Well known digital filters proposed for the restoration of these images have been investigated in this thesis. Particularly, Metz filter and a two-step filter have been extensively studied by the FROC methodology. The effectiveness and practical limitations of the FROC methodology in the assessment of nuclear medicine images have also been investigated. It was observed from the results that the closeness of test patterns to the real clinical cases was a crucial factor for a successful assessment. Therefore, a method to simulate clinical bone scans with focal abnormalities at a given depth has been developed in this thesis. A binormal model is used for the analysis of the FROC and AFROC results. A method has been developed in this thesis to determine the parameters that completely specify the binormal model. Using this method it has been shown in this work that the two-step filter may be useful in detecting focal abnormalities from complicated structures such as bone scans at strict criteria. It also has been observed in this work, that the Metz filter is useful for the detection of focal abnormalities in flat noise fields, but not in complicated structures such as bone scans.
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Wang, Silas Lancelot. "Clinical characteristics and treatment response to radiotherapy of optic nerve sheath meningiomas." [New Haven, Conn. : s.n.], 2007. http://ymtdl.med.yale.edu/theses/available/etd-08282007-150948/.
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Söderlund, Leifler Karin. "DNA repair pathways and the effect of radiotherapy in breast cancer." Doctoral thesis, Linköpings universitet, Onkologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17955.
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A large proportion of breast cancer patients are treated with radiotherapy. Ionising radiation induces different DNA damages, of which double-strand breaks are the most severe. They are mainly repaired by homologous recombination or non-homologous end-joining. Different protein complexes have central roles in these repair processes. In addition to the ability to repair DNA damage, cellular radiosensitivity is also affected by mitogenic signals that stimulate survival and inhibit apoptosis. The phosphatidylinositol 3-kinase (PI3-K)/AKT pathway controls cell proliferation, invasiveness and cell survival. AKT is regulated by upstream growth factor receptors, one of them being HER2 (also called ErbB2). HER2 is overexpressed in 15-30% of all breast cancers and associated with poor prognosis. In this thesis, we have studied factors that affect tumour cell resistance to ionising radiation. In Paper I, the role of HER2/PI3-K/AKT signalling in radiation resistance was investigated in two breast cancer cell lines. The results support the hypothesis that the HER2/PI3-K/AKT pathway is involved in resistance to radiation-induced apoptosis in breast cancer cells in which this signalling pathway is overstimulated. We also investigated if the protein expression of several DNA repair-associated proteins influence the prognosis and treatment response in early breast cancer. Moderate/strong expression of the MRE11/RAD50/NBS1 (MRN) complex predicted good response to radiotherapy, whereas patients with negative/weak MRN had no benefit from radiotherapy as compared to chemotherapy (Paper II). These results suggest that an intact MRNcomplex is important for the tumour-eradicating effect of radiotherapy. In Paper III, low expression of the BRCA1/BRCA2/RAD51 complex was associated with an aggressive phenotype, an increased risk of local recurrence and good response to radiotherapy. In Paper IV, we studied if a single nucleotide polymorphism, RAD51 135G/C, was related to RAD51 protein expression, prognosis and therapy resistance. We found that genotype was not correlated to neither protein expression nor prognosis. Patients who were G/G homozygotes had a significant benefit from radiotherapy. The results also suggested that the RAD51 135G/C polymorphism predicts the effect of chemotherapy in early breast cancer. In conclusion, DNA repair proteins are potential prognostic and predictive markers. The results indicate that proteins in different repair pathways may contribute differently to the effect of radiotherapy. Also, the HER2/PI3-K/AKT signalling pathway protects cells from radiation-induced apoptosis. In the future, it might be possible to target some of these proteins with inhibitory drugs to sensitise tumours to radiotherapy.
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Mehmood, Sajid. "Identification of predictive biomarkers of resistance to radiotherapy in rectal cancer." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:10110.
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Introduction and Aims: Neoadjuvant radiotherapy (RT) provides local control of disease in rectal cancer, however, the ability to predict response to RT is limited. The aim of this study was to establish a novel radioresistant (RR) rectal cancer cell line model and identify putative biomarkers of radioresistance using a microarray-based comparative proteomic platform. Methods: The inherent radiosensitivity of SW-837 and HRA-19 rectal adenocarcinoma parental cells was initially assessed. Following irradiation at 0, 2, 4, 6, 8 and 10 Grey (Gy) single doses using a linear accelerator, modified colony counting assays were performed. Dose response curves (DRCs) were plotted from calculated survival fraction (SF) values. To induce radioresistance, parental SW-837 and HRA-19 cells were irradiated in 8 and 4 Gy fractions, respectively, to a total dose of 48 Gy to generate novel sub-lines (termed SW-837 RR and HRA-19 RR). Following comparison of the DRCs from untreated parental cells and novel RR cells, total protein was extracted from radiosensitive parental (PN) cells and novel RR cells. Protein lysates from respective PN and RR cells were co-incubated onto Panorama antibody microarray (AbMa) slides containing 725 antibodies. Proteins which demonstrated at least 1.8-fold difference in expression between PN and RR cells were considered significant. The proteins with consistent differential expression and a putative role in radioresistance were selected for validation by immunohistochemistry (IHC), as a pilot study, in an archival series of 33 rectal cancer tissues categorised into ‘good response’ and ‘poor response’ groups based on tumour regression grading following long course chemoradiotherapy. Results: The comparison of DRCs revealed SW-837 RR cells to be significantly more radioresistant at 4, 6, 8 and 10 Gy and HRA-19 RR cells at 4, 6 and 8 Gy single doses than their respective parental cells (p<0.05). Comparative AbMa analyses of respective PN and RR cells demonstrated 62 differentially expressed proteins (DEPs) common to both RR cell lines. Of these, two apoptosis related proteins - DR4 and Bcl-2 were chosen for preliminary immunohistochemical validation for their putative role in radioresistance. The DR4 protein was found to be equally expressed whereas Bcl-2 demonstrated a trend towards reduced expression in 'poor-responder' rectal cancers compared with 'good-responders' that was not statistically significant. Conclusions: A radioresistant rectal cancer model consisting of novel SW-837 RR and HRA-19 RR cell sublines was successfully established and comparative proteomic analysis revealed a number of DEPs. In a small pilot IHC study, initial validation experiments showed no significant expression difference for DR4 and Bcl-2 proteins between ‘poor-responder’ and ‘good-responder’ rectal cancer patients. A panel of novel biomarkers from antibody array data would require further validation to determine their association with radioresistance before any firm conclusions can be drawn.
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Khoo, Vincent. "A study of conformal radiotherapy methods for brain and prostate cancer." Thesis, Institute of Cancer Research (University Of London), 2000. http://publications.icr.ac.uk/9718/.
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State-of-the-art radiotherapy involves a technology chain that includes 3D tumour imaging, 3D treatment planning, treatment delivery using conformal or intensity modulated techniques, and treatment verification. This thesis evaluates some of the recent imaging and planning developments to assess their role in optimisation of the technology chain for brain and prostate cancer. I focused on two major links in this technology chain. The 'imaging' link compared the use of MRI and CT in localising target volumes. An image registration protocol was developed to combine CT and MRI images in the brain. For the localisation of skull base meningiomas, MRI was found to provide contrasting information to CT. A composite target volume derived from both CT and MR information provided the most appropriate volume. For prostate radiotherapy, four MRI sequences were compared to CT. All MRI sequences provided improved localisation of relevant radiotherapy volumes-of-interest especially for the prostatic apex and rectum. The 'treatment planning' link investigated the impact of intra-fraction prostate motion for prostate planning margins, the creation of planning margins, the optimisation of beam orientations for prostate radiotherapy, and the utility of IMRT methods for brain tumours. Cine MR demonstrated a significant relationship between moderate rectal distension and increased rectal activity resulting in prostate motion. Mean prostate motion was < 5mm and lasted < 5% of a7 minute period indicating that the current 10mm prostate planning margin was adequate. The use of a 3D margin-growing method allowed the planning target margin to be accurately realised in all spatial orientations and avoided problems associated with 2D margin growing methods. A variety of co-planar arrangements using 3-, 4-, and 6-fields were evaluated for conformal prostate radiotherapy. Standard prostate plans could be optimised by proper consideration of beam orientations. A 3-field plan with gantry angles of 0", 90', 270' Provided the best rectal sparing for both prostate alone and prostate plus seminal vesicles volumes. Using this 3-field plan, dose escalation may be achieved with a smaller increase in predicted late rectal complications than with other 3-, 4-, or 6-field plans. An IMRT tomotherapy method was compared with conformal radiotherapy for convex shaped brain tumours to assess its potential for improved dose conformation. This IMRT method provided slightly improved PTV coverage but also higher OARs doses. However, these OARs doses remained within acceptable clinical limits. This IMRT tomotherapy method did not provide significant planning improvement compared to current conformal radiotherapy technique.
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Farajollahi, Ali Reza. "An investigation into the applications of polymer gel dosimetry in radiotherapy." Thesis, Online version, 1998. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.284699.
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Zhou, Tingyang. "Redox Mechanisms in Radiotherapy and Hypoxic Preconditioning." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469019913.
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Mishra, Nishikant. "A novel case-based reasoning approach to radiotherapy dose planning." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/29347/.
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In this thesis, novel Case-Based Reasoning (CBR) methods were developed to be included in CBRDP (Case-Based Reasoning Dose Planner) -an adaptive decision support system for radiotherapy dose planning. CBR is an artificial intelligence methodology which solves new problems by retrieving solutions to previously solved similar problems stored in a case base. The focus of this research is on dose planning for prostate cancer patients. The records of patients successfully treated in the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK, were stored in a case base and were exploited using case-based reasoning for future decision making. After each successful run of the system, a group based Simulated Annealing (SA) algorithm automatically searches for an optimal/near optimal combination of feature weights to be used in the future retrieval process of CBR. A number of research issues associated with the prostate cancer dose planning problem and the use of CBR are addressed including: (a) trade-off between the benefit of delivering a higher dose of radiation to cancer cells and the risk to damage surrounding organs, (b) deciding when and how much to violate the limitations of dose limits imposed to surrounding organs, (c) fusion of knowledge and experience gained over time in treating patients similar to the new one, (d) incorporation of the 5 years Progression Free Probability and success rate in the decision making process and (e) hybridisation of CBR with a novel group based simulated annealing algorithm to update knowledge/experience gained in treating patients over time. The efficiency of the proposed system was validated using real data sets collected from the Nottingham University Hospitals. Experiments based on a leave-one-out strategy demonstrated that for most of the patients, the dose plans generated by our approach are coherent with the dose plans prescribed by an experienced oncologist or even better. This system may play a vital role to assist the oncologist in making a better decision in less time; it incorporates the success rate of previously treated similar patients in the dose planning for a new patient and it can also be used in teaching and training processes. In addition, the developed method is generic in nature and can be used to solve similar non-linear real world complex problems.
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Davies, Elizabeth. "The quality of survival of patients with malignant cerebal glioma following radiotherapy." Thesis, Queen Mary, University of London, 1998. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1664.
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Objective- To describe survival, disability and morbidity after radiotherapy for malignant glioma and explore patient and relative experience. Design - Home follow-up of patients and relative over up to 24 months and of relatives after bereavement. Setting - Six London hospitals Subjects- 92 patients receiving radiotherapy (83 recruited at diagnosis; 9 after radiotherapy) and 85 relatives. 56 bereaved relatives. Main outcome measures- Survival, time free from disability, and changes in disability after treatment assessed, or deduced retrospectively, using interviewer observation, patient and relative reports, case note review and discussion with medical staff. A semi-structured interview designed for the study assessed awareness of the likely prognosis, distress, dissatisfaction with radiotherapy and perception of severe problems in everyday life. Results - 6,12 and 24 month survivals were 70%, 39% and 10%. Age, World Health Organisation clinical performance status, extent of surgery, and epilepsy each influenced survival. The Medical Research Council prognostic index was also significantly related to survival. Multivariate analysis showed that initial clinical performance status was the most important aspect of the index. Most (80%;4 9/61) patients with a clinical performance status of 0,1 or 2 lived at least 6 months before becoming permanently disabled. Of those with an initial good clinical performance status( 0-2) who survived 6 months after radiotherapy 69% (36/52) experienced either clinical deterioration or severe tiredness after treatment. Severely disabled patients (clinical performance status 3 or 4) gained little benefit. 75 patients and 66 relatives were interviewed at diagnosis, 59 patients after radiotherapy and 27 after deterioration. As they began radiotherapy most patients understood that they suffered from a brain tumour (95% ;7 1/75), but only one quarter (19/75) seemed fully aware of the poor prognosis. Others were unaware (43%; 32/75) or only partly aware (32%; 24/75). The more aware patients were more distressed. Relatives were three times more likely to be aware of the prognosis (67%; 44/66) and were more distressed. Although 39% (29/75) of patients initially made negative comments about radiotherapy, only 17% (13/75) were completely dissatisfied. The decision to accept radiotherapy could be discussed directly with 19 fully aware patients. Twelve found radiotherapy acceptable if it were medically advised or if it improved survival. Assessed by their own reports of symptoms only 40% of patients improved or achieved a period of stability, yet dissatisfaction with treatment did not increase. Bereaved relatives' judgements about quality of life and the value of radiotherapy were strongly related to the patient's initial disability and distress. Short periods of survival between six and 12 months were felt worthwhile. Conclusions- Severely disabled patients gain little benefit from radiotherapy and those not so disabled may experience considerable adverse effects. The lack of awareness of the prognosis, however, makes it difficult to explore with patients directly the possible trade off between quality and length of life. Relatives were more aware, more distressed and often concerned to protect patients from full awareness. However most aware patients accepted radiotherapy for the chance of improved survival and bereaved relatives valued relatively small periods of survival free from disability and distress. Conceptualising these questions as rational choices ignores therefore the social and emotional context of life threatening disease.
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Parker, Alexandra. "Risk stratification in rectal cancer : identifying tumours resistant to pre-operative radiotherapy." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/3157.
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Substantial progress has been made in the last few decades in the therapeutic and surgical treatment of CRC designed to improve survival. However, treatments tailored to the individual patient based on the mutation and gene expression profiles of CRC remain elusive. Rectal cancer, in particular, has come under scrutiny because of the wide variation in response rates to neoadjuvant radiotherapy, which may be linked to the high degree of hypoxia observed in this cancer. The cell killing potential of radiation is determined by the presence of oxygen and reactive oxygen species (ROS). ROS can be induced during inflammation and may cause genetic damage and cellular transformation, aiding radiation-induced DNA damage. Dual oxidase 2 (DUOX2) is a major source of ROS in the intestine and this study aims to evaluate the expression of DUOX2 and its maturation factor (DUOXA2) in both normal and neoplastic tissue, including rectal cancer, to determine whether oxygen tension can influence gene expression and to measure the outcome of exposure to irradiation (IR) in rectal cancer cell lines expressing different levels of DUOX2/DUOXA2. MicroRNAs (miRNAs) were also investigated as potential markers of hypoxia in rectal cancer cell lines and tissue. DUOX2 and DUOXA2 expression was found to be low in normal mucosal tissue, highly expressed in adenomas and moderately expressed in cancers, indicating a potential link between elevated ROS levels and tumour progression. Rectal cancer cell lines were used to show in vitro that DUOX2 expression was upregulated in response to a reduction in oxygen tension (2 % O2) and that the alteration in DUOX2 expression was independent of COX2 and HIF-1α expression. With the addition of IR, cells with high DUOX2 expression showed high levels of DNA damage and low numbers of stem-like cells (CD24) indicating susceptibility to IR. Cells with low DUOX2 expression showed low levels of DNA damage, high survival rate and a high quantity of CD24+ cells indicating resistance to IR. A number of consistently upregulated miRNAs were also identified in cells lines maintained in hypoxia. Follow-up investigations showed miR-210 to be consistently upregulated in hypoxic regions of rectal cancer and to target the iron sulphur cluster homolog (ISCU) gene both in vitro and in vivo. ISCU is an essential part of the mitochondrial electron transport chain and can control ROS production. Both DUOX2 and miR-210 have significant promise as markers of hypoxia in rectal cancers and warrant further investigation as markers of response to neoadjuvant radiotherapy.
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Jammal, Ghada. "Multiscale image restoration in nuclear medicine." Phd thesis, [S.l.] : [s.n.], 2001. http://elib.tu-darmstadt.de/diss/000100/GJammal.pdf.
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Darwesh, Reem. "Motion correction in nuclear medicine imaging." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664310.
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Patient motion either internal (organ motion) or external (body movement) can produce artefacts that can adversely affect nuclear medicine imaging. Motion artefacts can impair diagnostic information and potentially affect the image findings and prognosis for patients. The goal of this work was to investigate the effect of motion on nuclear medicine imaging and to improve image quality, lesion detectability, and tumour volume delineation by applying motion correction techniques. To investigate the effects of motion under controlled simulated conditions, a three dimensional phantom drive system was designed and constructed suitable for use with planar, SPECT, PET and CT scanners. The system was used with a range of nuclear medicine phantoms for testing proof of principle with planar, SPECT and PET imaging prior to undertake further work involving patients. Planar phantom and patient 99mTc_DMSA studies demonstrated improvements in image quality by the application of motion correction techniques. A comparison between the motion correction software using dynamic frame and list mode data showed that "MOCO" software with the use of the list mode data produced the best quantification results with phantom data, whereas determining the best approach was more difficult with patient data. The potential of using list mode data as an improved method of combining data into frames for subsequent analysis was demonstrated. Motion correction techniques would appear to offer great potential in lung imaging. Respiratory gated SPECT phantom studies have been carried out to simulate the visualisation of small defects in the lung. The CNRs and alternative free response receiver operating characteristic (AFROC) analysis have demonstrated that summing the gated data after the application of motion correction software significantly improved image quality, observer confidence and small defect detectability (less than 20 mm, p=O.0002). The results of these studies have shown the promising role of "MCFLIRT" software as a motion correction tool with gated SPECT data. Tumour volume delineation was investigated on PET images both with and without motion. The accuracy and consistency of the gradient-based software method for segmentation in PET images, which is commercially available from Mimvista Ltd was investigated. The results of comparing the measured volumes to the true volumes indicated significant differences (p=O.0005). It was found that the Signal:Background ratio and registering the PET to the CT data have significant effects on volume measurements, whereas, the effect of using different grey scale and plane of orientation were not found to have significant effects on the volume measurement. Motion correction techniques also showed to be potentially beneficial in PET imaging. Improvement in volume measurement as a result of summing the motion corrected gated data was demonstrated. The results of these studies have also shown the promising role of "MCFLIRT" as a motion correction tool with gated PET data.
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Jose, Romina Marie Johnston. "Analysis of renal nuclear medicine images." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342249.
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Whalley, D. R. "Image processing techniques in nuclear medicine." Thesis, Open University, 1989. http://oro.open.ac.uk/57292/.
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The application of image processing techniques to radionuclide images acquired on a gamma camera - computer system has been investigated. Hepatic perfusion imaging studies with 99TcID-tin colloid were performed in patients with primary colorectal carcimma. The hepatic perfusion index perform~ poorly in the detection of those patients with occult or overt hepatic metastastes, as did mean transit times of liver colloid flow derived from deconvolution analysis. A discriminant function was developed which separated those patients with occult metastases from those without liver disease. A fully automatic algorithm to derive a left ventricular edge from each frame of an ECG gated cardiac blood pool study was developed and validated in patient studies. Left ventricular ejection fractions calculated from count rates within the edge were reproducible and correlated well with ejection fractions derived from the same images by a manual technique, and with ejection fractions derived from left ventricular cineangiography. Studies were performed in patients to evaluate the effectiveness of tomographic imaging of the myocardial perfusion imaging agent 99TcID-tBIN for detection of ischaemic heart disease. TOmographic reconstructions in the planes of the axes of the left ventricle gave better results than transaxial reconstructions or planar imaging. Choice of the optimum reconstruction filter for use in tomography using 99Tdffi-tBIN was examined by means of patient am phantom studies. These showed that more accurate diagnoses and better reconstructions were obtained with smoothing filters than by the use of sharp reconstruction filters. This work shows that optimum image processing techniques must be established to attain the best possible results with new radiopharmaceuticals for nuclear medicine investigations.
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Gardner, Joseph. "EPID-based Dose Verification for Adaptive Radiotherapy." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2941.
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Dose verification is a critical component of adaptive radiotherapy, as it provides a measurement of treatment delivery success. Based on the measured outcome, the plan may be adapted to account for differences between the planned dose and the delivered dose. Although placement of an EPID behind the patient during treatment allows for exit dosimetry which may be used to reconstruct the delivered patient dose via backprojection of the fluence, there have not been any studies examining the basic assumption of backprojection-based dose verification: that deviations between the expected and delivered exit fluences are totally caused by errors in the delivered fluence, and not caused by patient geometry changes. In this dissertation, the validity of this assumption is tested. Exit fluence deviations caused by machine fluence delivery errors are measured as well as those caused by interfractional changes in the patient anatomy. Dose reconstruction errors resulting from the backprojection assumption are assessed. Correlations are examined between exit fluence deviations and patient dose reconstruction deviations. Based on these correlations, a decision tree is proposed detailing when caution should be taken in performing dose reconstruction to achieve delivery verification. Finally, a semi-automated dose verification tool is constructed for both clinical and research purposes.
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Royle, Georgina. "Towards quantitative intra-nuclear dose mapping of auger emitting radionuclides used for targeted radiotherapy." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:83c94d40-91a2-4175-b208-b5ea1bd5a207.
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Targeted radiotherapy (TRT) is a technique which allows for individual cancer cells to be targeted by radiation. However, there is variation in uptake at the whole body, organ, cellular and subcellular levels. This distribution affects the biological efficacy of the TRT agents. To address this problem, novel techniques have been developed and demonstrated. These aim to provide quantitative information about the spatial distribution of Auger electron (AE) emitting radiopharmaceuticals at the subcellular level. Two methods have been developed. The first, photoresist autoradiography (PAR), uses photoresists as an autoradiography substrate, and the second uses microautoradiography (MAR) and a transmission electron microscope (TEM). The techniques have been demonstrated using the AE emitter indium-111. Firstly, PAR is demonstrated using poly (methyl methacrylate) (PMMA). Photoresists were exposed to indium-111 which had been internalised into cells, and the photoresists were analysed using atomic force microscopy (AFM). The technique has a theoretical resolution in the nanometre range and was able to demonstrate cellular patterns on the micron scale. To gain quantitative information, the photoresist response (depth of pattern) was calibrated as a function of electron fluence and a model of the patterns was created. Combining the calibration data with the point source model allowed the position and intensity of the internalised source terms to be estimated using the PAR method. Secondly, a technique for electron microscope-microautoradiography (EM-MAR) was developed. The processing conditions of the MAR technique were determined and staining techniques developed, to produce high quality TEM micrographs. A time course experiment showed the distribution and variation in the uptake of the radiopharmaceutical at the cellular level. Both techniques are able to provide information about the subcellular distribution of the radioactivity at a higher resolution than current techniques. Both enable the collection of information which can be used in microdosimetric calculations.
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ElFadl, Dalia. "Proteomic identification and validation of biomarkers associated with resistance to radiotherapy in breast cancer." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:13996.
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Background: Breast cancer is an important health issue. The majority of patients present with early stage cancer and are therefore candidates for breast conserving surgery and radiotherapy. A proportion will suffer from local recurrence, which may be secondary to radiotherapy resistance. Though extensive research has been carried out into molecular markers of resistance, none has been applied to clinical practice, which suggests that the search for such markers is wanting. Materials and Methods: The principle of the biomarker discovery pipeline was applied and cancer cell lines were utilised for the first two phases of this project. Protein expression in radiosensitive and radioresistant cell lines was compared using, first antibody microarray technology (AbMA), as a screening tool, and secondly, western blot (WB) technique as a verification tool. The final stage was clinical validation. A clinical series of archival breast cancer tissue was identified; one representing a radiosensitive group, and a second representing a radioresistant group. Immunohistochemistry (IHC) was then employed to compare the differential protein expression between the two. Results: The AbMA technology was successfully utilised to yield 63 potential biomarkers of radioresistance. Of these, zyxin, PIASx and DR4 were confirmed using WB. Clinical validation showed no association between zyxin and radioresistance; this protein had been previously suggested to be associated with cellular stress. DR4 has been clinically validated using IHC, and has therefore been identified as a putative biomarker using all three techniques. In addition, the association between radioresistance and the 26S proteasome was clinically validated. Discussion: This work supports the role of zyxin as a stress associated protein. The underexpression of DR4, a pro-apoptotic factor, and 26S proteasome, a major effector in the protein proteolysis machinery and cell cycle has been proven. These two proteins present putative markers of radioresistance. The possibility of pre-treatment definition of the expected response to radiation therapy would improve patients’ outcome. Radiation can be offered only to those expected to respond to it, while others would be offered other treatment modalities.
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Roussakis, Yiannis G. "Strategies for adaptive radiotherapy : towards clinically efficient workflows." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6611/.
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Adaptive radiotherapy (ART) aims to adapt the treatment plan to account for inter-fraction anatomical variations, based on online acquired images. However, ART workflows are not –yet– routinely used in clinical practice, primarily due to the dramatic increase of the workload required and the inadequate understanding of optimal methods to maximise clinical benefit. This thesis reports on investigations of procedures for the automation of the ART process and the identification of optimal adaptation methodologies. Investigated auto-segmentation algorithms were found insufficient for an automated workflow, while a hybrid deformable image registration (DIR), incorporating both intensity based and feature-based components, revealed the most accurate and robust performance. An evaluation method was proposed for interfraction treatment monitoring through dose accumulation following DIR. The robustness of several treatment methods to observable anatomical changes were investigated, highlighting cases whereby substantial dosimetric consequences may arise. Offline ART workflows were explored, specifically investigating the effects of treatment monitoring frequency, adaptation method (simple re-plan or re-optimisation addressing cumulative dose), and adaptation timing. Contrary to simple re-planning, re-optimisation demonstrated its ability to compensate for under-/over-dose, however, non-uniform dose distributions and hot-spots may be generated. Therefore established planning techniques are applicable for re-planning while advanced approaches are required for treatment re-optimisation accounting for radiobiological consequences.
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PAIVA, FABIO de. "Estudo das respostas de TLD tipo LiF para caracterização de campos mistos." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26930.
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A Terapia por Captura de Nêutrons, NCT (Neutron Capture Therapy) é uma técnica radioterápica em que a energia útil do tratamento vem da energia liberada em uma reação nuclear e não do feixe primário, como comumente utilizado em outros procedimentos radioterápicos. O Boro, por constituir-se em um elemento de baixa toxicidade e por apresentar um isótopo (10B) com alta seção de choque para a reação 10B(n,α)7Li tem sido o elemento mais utilizado nas pesquisas que visam o aprimoramento e a promoção desta técnica, derivando daí o termo BNCT (Boron Neutron Capture Therapy). Para fins de pesquisa em BNCT foi construída ao longo de um dos extratores de feixes (BH - Beam Hole) do reator IEA-R1 uma instalação, onde filtros e moderadores são posicionados entre o núcleo do reator e a posição de irradiação com o objetivo de modular o feixe de irradiação, otimizando a componente útil do feixe, os nêutrons térmicos, e reduzindo os contaminantes, raios gama e nêutrons em outras faixas energéticas. Tem-se realizado estudos visando a implementação de melhorias na caracterização e otimização do feixe obtido nesse arranjo instalado no BH-3. Atualmente a monitoração dos nêutrons é feita através de folhas de ativação, e a componente gama pelo TLD-400. Uma nova metodologia de monitoração tem sido estudada pelo grupo. A referida técnica consiste em usar TLDs de tipos diferentes, ou seja, que possuam sensibilidades distintas aos nêutrons térmicos, em virtude de diferenças na concentração dos isótopos de Lítio. No estudo dessa nova metodologia têm sido usados os TLD-600 e TLD-700. Este trabalho propõe uma metodologia usando o par TLD-100 e TLD-700. Inicialmente foi verificada a reprodutibilidade das respostas dos TLDs 700, 400 e 100 frente a campos gama puro e campos mistos, gama e nêutron. Campos estes obtidos em arranjos usando fontes de 60Co e 241AmBe. A partir de simulações usando o VI MCNP5 foi projetado e construído um Irradiador de campos mistos, que permitiu expor os dosímetros em campos mistos com diferentes espectros energéticos. As condições criadas no irradiador permitiram verificar, como a resposta do TLD é modificada pelas mudanças no espectro energético de um campo misto gama e nêutrons de baixo fluxo. O irradiador de campo misto permitiu condições para estabelecer uma relação entre o formato da curva termoluminescente e a composição do campo misto. A relação estabelecida relaciona o fluxo relativo e a razão entre a resposta das duas regiões de interesse dos TLDs 700 e 100. A partir de campos mistos com condições controladas, esse trabalho permitiu verificar a viabilidade do uso do par de TLD-100 e TLD-700 para monitoração de nêutrons térmicos na instalação de BNCT.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Valastyán, Iván. "Applications of tomographic imaging in nuclear medicine." Licentiate thesis, KTH, Physics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4187.
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Valastyán, Iván. "Applications of tomographic imaging in nuclear medicine /." Stockholm : School of engineering sciences, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4187.
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Eskin, Joshua Daniel 1960. "Semiconductor gamma-ray detectors for nuclear medicine." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/288740.
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Semiconductor-based gamma-ray-imaging detectors are under development for use in high-resolution nuclear medicine imaging applications. These detectors, based on cadmium zinc telluride, hold great promise for delivering improved spatial resolution and detection efficiency over current methods. This dissertation presents work done on three fronts, all directed toward enhancing the practicality of these imaging devices. Electronic readout systems were built to produce gamma-ray images from the raw signals generated by the imagers. Mathematical models were developed to describe the detection process in detail. Finally, a method was developed for recovering the energy spectrum of the original source by using maximum-likelihood estimation techniques. Two electronics systems were built to read out signals from the imaging detectors. The first system takes signals from a 48 x 48-pixel array at 500 k samples per second. Pulse-height histograms are formed for each pixel in the detector, all in real time. A second system was built to read out four 64 x 64 arrays at 4 million pixels per second. This system is based on digital signal processors and flexible software, making it easily adaptable to new imaging tasks. A mathematical model of the detection process was developed as a tool for evaluating possible detector designs. One part of the model describes how the mobile charge carriers, which are released when a gamma ray is absorbed in a photoelectric interaction, induce signals in a readout circuit. Induced signals follow a "near-field effect," wherein only carriers moving close to a pixel electrode produce significant signal. Detector pixels having lateral dimensions that are small compared to the detector thickness will develop a signal primarily due to a single carrier type. This effect is confirmed experimentally in time-resolved measurements and with pulse-height spectra. The second part of the model is a simulation of scattering processes that take place when a gamma ray is absorbed within the detector volume. A separate simulation predicts the spreading of charge carriers due to diffusion and electrostatic forces. The models are used in a technique to improve the energy resolution of the detectors by estimation of the source spectrum using the Expectation-Maximization algorithm.
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Oliveira, V. A. "Maximum entropy image restoration in nuclear medicine." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235282.
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Hanvey, Scott Lewis. "Magnetic resonance imaging to improve structural localisation in radiotherapy planning." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/5117/.
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The purpose of this thesis is to develop the role of magnetic resonance imaging (MRI) in the radiotherapy (RT) planning process. This began by assessing a prototype inline three-dimensional distortion correction algorithm. A number of quality assurance tests were conducted using different test objects and the 3D distortion correction algorithm was compared with the standard two-dimensional version available for clinical use on the MRI system. Scanning patients using MRI in the RT position within an immobilisation mask can be problematic, since the multi-channel head coils typically used in diagnostic imaging, are not compatible with the immobilisation mask. To assess the image quality which can be obtained with MR imaging in the RT position, various MRI quality assurance phantoms were positioned within an immobilisation mask and a series of image quality tests were performed on four imaging coils compatible with the immobilisation mask. It was shown that only the 4-channel cardiac coil delivered comparable image quality to a multi-channel head coil. An investigation was performed to demonstrate how MRI patient position protocols influence registration quality in patients with prostate cancer undergoing radical RT. The consequences for target volume definition and dose coverage with RT planning were also assessed. Twenty patients with prostate cancer underwent a computed tomography (CT) scan in the RT position, a diagnostic MRI scan and an MRI scan in the RT position. The CT datasets were independently registered with the two MRI set-ups and the quality of registration was compared. This study demonstrated that registering CT and MR images in the RT position provides a statistically significant improvement in registration quality, target definition and target volume dose coverage for patients with prostate cancer. A similar study was performed on twenty-two patients with oropharyngeal cancer undergoing radical RT. It was shown that when patients with oropharyngeal cancer undergo an MRI in the RT position there are significant improvements in CT-MR image registration, target definition and target volume dose coverage.
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Carr, Simon David. "Assessing the effects of radiotherapy on head and neck squamous cell carcinoma using microfluidic techniques." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8396.
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Objective The aim of this study was to investigate how HNSCC tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device, respond to radiation treatment. Materials and Methods 35 patients with HNSCC were recruited; in addition liver tissue from 5 Wistar rats was used. A glass microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimise the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5x2 Gy. Cell death was assessed in the tissue effluent using the soluble markers LDH and cytochrome c, and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Radiation-induced DNA strand breaks were detected using the TUNEL assay. Results A significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC it was seen after 40 Gy, compared to the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single dose radiation. There was a significant increase in apoptotic index between the non-irradiated HNSCC tissue and irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. As with the apoptotic index, there was a significant increase in radiation-induced DNA breaks between the non-irradiated and the irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. Conclusion This microfluidic technique can be used to study the effects of radiation on HNSCC tissue. The device was capable of maintaining the HNSCC in a viable state, without it undergoing significant apoptosis or DNA damage and can be used to demonstrate the relationship between radiotherapy dose and radiation-induced cell death using tissue-based cell death markers. This study is a significant step towards achieving the ultimate goal of developing this device as a tool, capable of predicting a patient’s response to radiotherapy prior to the commencement of treatment.
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Coetzee, Nicolene. "A phantom based evaluation on the effects of patient breathing motion on Stereotactic Body Radiotherapy treatment volumes." Master's thesis, Faculty of Health Sciences, 2020. http://hdl.handle.net/11427/32181.
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Aim: The aim of the study was to design an upper body phantom to mimic the movement of the lesion inside the lungs during a breathing cycle. Phantom design included an assessment of the motion observed for lung lesions, identification of suitable phantom materials as well as design of a motorized arm to mimic the movements observed inside the lung area of the phantom. Introduction: Expansion margins are added to clinical target volumes contoured by Oncologists in order to safeguard against under- or over-treatment of the target volume. They are designed to account for errors during setup, inaccuracies on the linear accelerator, and movement of targets inside the patient. If the margins are too small, there is a risk that the lesion/target may not receive the necessary dose, due to being partially missed. On the other hand, if the margins are too wide, the lesion will be covered, but normal tissue may receive unnecessary dose, resulting in additional side effects to the patient. Assessment of the impact of these margins is not possible in a static phantom and the availability of a low-cost motorized phantom would assist in the validation of these margins. Method: Previously treated patients' 4D CT scanning data were used to quantify the amount of movement seen for lesions within the lung. A phantom was then designed and built in an attempt to mimic both patient anatomy and movement. Materials were identified to replicate anatomical shape and densities of various organs in the thorax, as seen on CT scan data. Two treatment planning systems (Monaco, (Elekta) and Eclipse (Varian)) were used to determine the dosimetric characteristics of the materials. This was compared to actual dose as delivered by a linear accelerator (Elekta Synergy). Results: Paths were calculated from the breathing cycles during the 4D-CT scan sets and templates designed to mimic these movements. A thorax phantom was built with the appropriate materials suitable and matched densities to replicate a human thorax. Comparing transmission for these materials on a linear accelerator for 6MV and 10MV energy, the deviation from planned versus measured dose varied between 1.67% to 3.32% and 0.45% to 2.30%, respectively for the silicon material and between 0.77% to 3.22% and 0.17% to 2.57% for the 3D printed bone for 6MV and 10MV. iv Conclusion: The measurements done on the linear accelerator matched closely with the calculated values on the treatment planning system for transmission through the materials in the customised phantom. Various proposals were put forward to mimic the movement of the targets within the lung regions. However, it was not possible to manufacture a mechanically based working model due to the small movements observed (<5mm). It is recommended that a robotic solution be investigated as alternative to mimic these small movements.
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Aguwa, Kasarachi. "Radiation Dose Study in Nuclear Medicine Using GATE." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/593601.
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Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Janet al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiation dose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.
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Harvey, Darren Keith. "Design of a Compton camera for nuclear medicine." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284644.
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Teles, Patricia Rebello. "Hadronterapia: abordagem semiclássica da perda de energia, efeitos da fragmentação nuclear e taxa de reação." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-27112014-081805/.
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O objetivo primordial da Radioterapia é fornecer ao tumor uma dose de radiação suficientemente alta e uniformemente distribuída, de forma a poupar os tecidos adjacentes saudáveis dos efeitos ela radiação. Alcançar esse objetivo em sua plenitude é muito difícil devido à vários fatores, como por exemplo uma determinação eficiente do volume a ser tratado (através ela aquisição ele imagens tomográficas ela localização elo tumor no corpo) e também a realização eficaz da distribuição da. dose de radiação (que deve ser tridimensionalmente uniforme e alta o suficiente para erradicar a doença). Atualmente, a técnica de intensidade modulada do feixe (IMRT) usada na Radioterapia Convencional desempenha um avanço importante para o tratamento de tumores situados perto de estruturas anatômicas complexas, como é o caso dos tumores de próstata e de cabeça e pescoço. Essa moderna técnica conformacional já é aplicada nos tratamentos de tumores em vários hospitais nacionais, e citamos, como exemplo, o Hospital Sírio e Libanês, em São Paulo. No entanto, em países como os Estados Unidos, a Alemanha e o Japão, a radioterapia com partículas pesadas carregadas, como prótons c íons de carbono, tem sido desenvolvida há vários anos e demonstra sucesso absoluto no tratamento localizado ele tumores devido a deposição de energia característica dos feixes hadrônicos. A Hadronterapia, modalidade de tratamento ainda desconhecida no Brasil, é o objeto desse trabalho. Nele apresentamos a física básica envolvida no fenômeno da perda de energia dos projéteis, revisamos a dedução da conhecida fórmula ele Bethe-Bloch e, utilizando uma aproximação semi-clássica para obtenção da seção de choque da reação, obtemos os efeitos de uma interação nuclear considerada como uma perturbação à interação coulombiana dominante. Aplicamos também o modelo estatístico de Goldhaber para o cálculo dos efeitos da fragmentação nuclear induzida pelo projétil e, partindo de conceitos utilizados em astrofísica., calculamos a taxa de reação para estimar, quantitativamente, a influência da temperatura. na região do tumor neste processo.The aim of radiation therapy is to deliver the dose as high and as uniform as possible to diseased tissue sparing all the other parts, that is healthy and critical tissues, without causing unwanted and unnecessary side effects for the patient. Difficults to achieve this goal start with the determination of the three dimensional volumes of interest and end up in realizing a three-dimensional uniform and maximal as possible, the dose distribution. The technique of intensity-modulated radiotherapy (IMRT) as form of conformation in conventional radiation therapy is a real revolution. On the other hand, the use of therapeutic charged particles, as protons and carbon íons, is the technology of the actual future which is really the challenge in conformation of dose to targets, thanks to energy deposition characteristics of hadronic beams. The aim of this work is to review the basic physics concerning the treatment of localized tumors with charged particles by applying a semi-classical approach to obtain a dispersion in the equation of energy loss, originally derived by Hans Bethe and Felix Bloch. On a second moment we use statistical methods (Goldhaber statistic model) to estimate the energy of fragment after nuclear fragmentation processes and, in addition, we obtain a expression for the nuclear reaction rate to introduce how the temperature on tumor region would affect it.
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Enblom, Anna. "Nausea and vomiting in patients receiving acupuncture, sham acupuncture or standard care during radiotherapy." Doctoral thesis, Linköpings universitet, Omvårdnad, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17237.
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Background and aim: Many patients with cancer experience emesis (nausea and vomiting) during radiotherapy. The overall aim of this thesis was to improve the situation for patients with risk for emesis during radiotherapy, by evaluating emesis in patients receiving verum (genuine) acupuncture, sham (simulated) acupuncture or standard care during radiotherapy. Methods: In study I, a cross-sectional sample (n=368) treated with radiotherapy over various fields answered a study-specific questionnaire. In study II, 80 healthy volunteers were randomized to receive needling with verum acupuncture or non-penetrating telescopic sham needles by one of four physiotherapists. In study III, 215 patients were randomly allocated to verum (n=109) or non-penetrating telescopic sham (n=106) acupuncture during their entire radiotherapy period over abdominal or pelvic fields. The same 215 patients were also included in study IV. They were compared to 62 patients irradiated over abdominal or pelvic fields, selected from study I. Results: In study I, the weekly prevalence of nausea was 39 % in all radiotherapy-treated patients and 63 % in abdominal or pelvic irradiated patients. Age younger than 40 years and previous experience of nausea in other situations were characteristics associated with an increased risk for nausea. Of the 145 nauseous patients, 34 % considered their antiemetic treatment as insufficient. Patients with nausea reported lower level of quality of life compared to patients free from nausea. In study II, most individuals needled with verum (68 %) or sham (68 %) acupuncture could not identify needling type, and that blinding result varied from 55 to 80 % between the four therapists. In study III, nausea was experienced by 70 % (mean number of days=10.1) and 25 % vomited during the radiotherapy period. In the sham group 62 % experienced nausea (mean number of days=8.7) and 28 % vomited. Ninety five percent in the verum and 96 % in the sham group believed that the treatment had been effective for nausea. In both groups, 67 % experienced other positive effects, on relaxation, mood, sleep or pain-reduction, and 89 % were interested in receiving the treatment again. In study IV, the weekly prevalence of nausea and vomiting was 38 and 8 % in the verum group, 37 and 7 % in the sham group and 63 and 15 % in the standard care group. The nausea difference between the acupuncture and the standard care cohort was statistically significant, also after overall adjustments for potential confounding factors. The nausea intensity in the acupuncture cohort was lower compared to the standard care cohort (p=0.002). Patients who expected nausea had increased risk for nausea compared to patients who expected low risk for nausea (Relative risk 1.6). Conclusions and implications: Nausea was common during abdominal or pelvic field irradiation in patients receiving standard care. Verum acupuncture did not reduce emesis compared to sham acupuncture, while reduced emesis was seen in both patients treated with verum or sham acupuncture. Health-care professionals may consider identifying and treating patients with increased risk for nausea in advance. The telescopic sham needle was credible. Researchers may thus use and standardize the sham procedure in acupuncture control groups. The choice of performing acupuncture during radiotherapy cannot be based on arguments that the specific characters of verum acupuncture have effects on nausea. It is important to further study what components in the acupuncture procedures that produce the dramatic positive but yet not fully understood antiemetic effect, making it possible to use those components to further increase quality of care during radiotherapy.
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Widita, Rena Physics Faculty of Science UNSW. "Simultaneous optimization of beam positions for treatment planning and for image reconstruction in radiotherapy." Awarded by:University of New South Wales. School of Physics, 2006. http://handle.unsw.edu.au/1959.4/25774.
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From one treatment to the next, considerable effort is made to accurately position radiotherapy patients according to their treatment plans. However, some variation is unavoidable. The target volume and the organs at risk may also move within the patient and/or change shape during the treatment. Thus, it is important to be able to verify the success of the treatment by determining the position of patient and the dose deposited in the patient at each fraction. One possibility to achieve this, particularly when equipment, time and budgets are limited, would be to collect limited information while the patient is on the treatment couch. This research was aimed to develop a method for optimum beam position determination, for each patient-specific case. The optimized beam positions would balance the both treatment planning and image reconstruction, so that the patient???s image can be obtained during the treatment delivery using the information collected from the same angles as used for treatment. This will allow verification of the dose deposited in the patient for every fraction. Using a limited number of angles for image reconstruction, the dose to the patient can be minimized. This work has two major parts, beam position optimization for image reconstruction and beam position optimization for treatment planning. These two optimizations are then combined to obtain the optimum beam position for both image reconstruction and treatment planning. An objective function, projection correlation, was developed to investigate the image reconstruction method using limited information. Another objective function, the average optimization quality factor, was also introduced to optimize beam positions for treatment planning. Two optimization methods, the gradient descent method and the simulated annealing based on these objective functions were used to determine the beam angles. The results show that the projection correlation presents several advantages. It can be applied without any iterations, and it produces a fast algorithm. The present research will allow selection of the optimum beam positions without excessive computational cost for treatment planning and imaging. By combining the projection correlation and the average optimization quality factor together with more advanced image reconstruction software this could potentially be used in a clinical environment.
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Nguyen, Son Hung 1966. "Topographic classification of nuclear medicine images for tumor detection." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278117.
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Topographic classification is a nonlinear technique used to enhance nuclear medicine images for tumor detection. Second-order directional derivatives are computed at each pixel location after performing a least-squares fit of the underlying surface using a bivariate cubic polynomial. The eigenvalues and their corresponding eigenvectors computed from the Hessian matrix determine which topographic feature is assigned to the image pixel. Parameter selection for the mask size, curvature threshold, and angle thresholds are chosen to yield the "best" classified image. The classifier is applied to clinical images of cancer patients provided by the Department of Nuclear Medicine at the University of Arizona. Background noise associated with the photon-starved data is suppressed using a Difference-of-Gaussians (DOG) filter prior to pixel classification. Results indicate the feasibility of using this technique to isolate possible tumor sites which will assist the clinician during patient examination.