ESS - RADT - Radioterapia
URI permanente desta comunidade:
Navegar
Percorrer ESS - RADT - Radioterapia por data de Publicação
A mostrar 1 - 10 de 48
Resultados por página
Opções de ordenação
- Comparação dos efeitos secundários agudos da Radioterapia por intensidade modulada com a Radioterapia tridimensional conformada no carcinoma de próstataPublication . Pereira, A. V.; Fonte, D.; Alves, L.Introdução: Este trabalho tem como principal objectivo comparar os efeitos secundários agudos da Radioterapia por Intensidade Modulada (IMRT) e a Radioterapia Tridimensional Conformada (3 D-CRT) no carcinoma de Próstata; Materiais e métodos: Foram observados os processos clínicos de 30 doentes e analisados os efeitos colaterais da RT ocorridos no decurso do tratamento. Resultados: A percentagem de toxicidade aguda dermatológica foi superior no grupo tratado com 3D-CRT. Nenhum doente apresentou toxicidade aguda grave. Conclusões: O tamanho reduzido da amostra e a ausência de valores estatisticamente significativos, não permite concluir a influência da técnica de RT no desenvolvimento de efeitos secundários agudos.
- Inter-speaker speech variability assessment using statistical deformable models from 3.0 Tesla magnetic resonance imagesPublication . Vasconcelos, Maria J. M.; Ventura, Sandra Moreira Rua; Freitas, Diamantino R. S.; Tavares, João Manuel R. S.The morphological and dynamic characterisation of the vocal tract during speech production has been gaining greater attention due to the motivation of the latest improvements in magnetic resonance (MR) imaging; namely, with the use of higher magnetic fields, such as 3.0 Tesla. In this work, the automatic study of the vocal tract from 3.0 Tesla MR images was assessed through the application of statistical deformable models. Therefore, the primary goal focused on the analysis of the shape of the vocal tract during the articulation of European Portuguese sounds, followed by the evaluation of the results concerning the automatic segmentation, i.e. identification of the vocal tract in new MR images. In what concerns speech production, this is the first attempt to automatically characterise and reconstruct the vocal tract shape of 3.0 Tesla MR images by using deformable models; particularly, by using active and appearance shape models. The achieved results clearly evidence the adequacy and advantage of the automatic analysis of the 3.0 Tesla MR images of these deformable models in order to extract the vocal tract shape and assess the involved articulatory movements. These achievements are mostly required, for example, for a better knowledge of speech production, mainly of patients suffering from articulatory disorders, and to build enhanced speech synthesizer models.
- Predicting Xerostomia induced by IMRT treatments: A logistic regression approachPublication . Soares, Inês; Dias, Joana; Rocha, Humberto; Lopes, Maria do Carmo; Costa Ferreira, BrigidaRadiotherapy is one of the main treatments used against cancer. Radiotherapy uses radiation to destroy cancerous cells trying, at the same time, to minimize the damages in healthy tissues. The planning of a radiotherapy treatment is patient dependent, resulting in a lengthy trial and error procedure until a treatment complying as most as possible with the medical prescription is found. Intensity Modulated Radiation Therapy (IMRT) is one technique of radiation treatment that allows the achievement of a high degree of conformity between the area to be treated and the dose absorbed by healthy tissues. Nevertheless, it is still not possible to eliminate completely the potential treatments’ side-effects. In this retrospective study we use the clinical data from patients with head-and-neck cancer treated at the Portuguese Institute of Oncology of Coimbra and explore the possibility of classifying new and untreated patients according to the probability of xerostomia 12 months after the beginning of IMRT treatments by using a logistic regression approach. The results obtained show that the classifier presents a high discriminative ability in predicting the binary response “at risk for xerostomia at 12 months”
- Estratégia preventiva da mucosite oral em doentes com tumores de cabeça e pescoço. Experiência com fosfato de cálcioPublication . Mousinho, Filipa; Costa Ferreira, Brigida; Khouri, Leila; Guardado, Maria João; Vale Marques, Rui; Rodrigues, Joana M.C.; Melo, GilbertoA mucosite oral é uma consequência frequente no tratamento de doentes oncológicos, nomeadamente de cabeça e pescoço. Refere-se a lesões eritematosas e ulcerativas da mucosa oral em doentes submetidos a radioterapia e/ou quimioterapia. Estas lesões são muitas vezes dolorosas e podem comprometer a nutrição, a hidratação, a higiene oral e ainda aumentar o risco de infecção sistémica. Infecções associadas a mucosite oral podem ser a causa de sepsis em doentes imunodeprimidos.
- Morfometria do trato vocal por ressonância magnética: simulação de padrões patológicos articulatóriosPublication . Ventura, Sandra Moreira Rua; Freitas, Diamantino Rui S.; Ramos, Isabel Maria A.; Tavares, João Manuel R. S.Introdução – A análise da forma ou morfometria de estruturas anatómicas, como o trato vocal, pode ser efetuada a partir de imagens bidimensionais (2D) como de aquisições volumétricas (3D) de ressonância magnética (RM). Esta técnica de imagem tem vindo a ter uma utilização crescente no estudo da produção da fala. Objetivos – Demonstrar como pode ser efetuada a morfometria do trato vocal a partir da imagem por ressonância magnética e ainda apresentar padrões anatómicos normais durante a produção das vogais [i a u] e dois padrões articulatórios patológicos em contexto simulado. Métodos – As imagens consideradas foram recolhidas a partir de aquisições 2D (Turbo Spin-eco) e 3D (Flash Gradiente-Eco) de RM em quatro sujeitos durante a produção das vogais em estudo; adicionalmente procedeu-se à avaliação de duas perturbações articulatórias usando o mesmo protocolo de RM. A morfometria do trato vocal foi extraída com recurso a técnicas manuais (para extração de cinco medidas articulatórias) e automáticas (para determinação de volumes) de processamento e análise de imagem. Resultados – Foi possível analisar todo o trato vocal, incluindo a posição e a forma dos articuladores, tendo por base cinco medidas descritivas do posicionamento destes órgãos durante a produção das vogais. A determinação destas medições permitiu identificar quais as estratégias mais comummente adotadas na produção de cada som, nomeadamente a postura articulatória e a variação de cada medida para cada um dos sujeitos em estudo. No contexto de voz falada intersujeitos, foi notória a variabilidade nos volumes estimados do trato vocal para cada som e, em especial, o aumento do volume do trato vocal na perturbação articulatória de sigmatismo. Conclusão – A imagem por RM é, sem dúvida, uma técnica promissora no estudo da fala, inócua, não-invasiva e que fornece informação fiável da morfometria do trato vocal.
- Noncoplanar beam angle optimization in IMRT treatment planning using pattern search methodsPublication . Rocha, Humberto; Dias, Joana M; Costa Ferreira, Brigida; Lopes, Maria CRadiation therapy is used to treat localized cancers, aiming to deliver a dose of radiation to the tumor volume to sterilize all cancer cells while minimizing the collateral effects on the surrounding healthy organs and tissues. The planning of radiation therapy treatments requires decisions regarding the angles used for radiation incidence, the fluence intensities and, if multileaf collimators are used, the definition of the leaf sequencing. The beam angle optimization problem consists in finding the optimal number and incidence directions of the irradiation beams. The selection of appropriate radiation incidence directions is important for the quality of the treatment. However, the possibility of improving the quality of treatment plans by an optimized selection of the beam incidences is seldom done in the clinical practice. Adding the possibility for noncoplanar incidences is even more rarely used. Nevertheless, the advantage of noncoplanar beams is well known. The optimization of noncoplanar beam incidences may further allow the reduction of the number of beams needed to reach a clinically acceptable plan. In this paper we present the benefits of using pattern search methods for the optimization of the highly non-convex noncoplanar beam angle optimization problem.
- Apparent diffusion coefficient in the analysis of prostate cancerPublication . Adubeiro, Nuno; Nogueira, Luísa; Ribeiro, Eduardo; Alves, Sandra; Ferreira, Hugo; La Fuente, JoséThe multiparametric magnetic resonance imaging (MPMRI) approach, has allowed the diagnostic performance in the detection and characterization of prostate cancer (PCa). Diffusion-weighted imaging (DWI), is an important technique in the MPMRI, that provides qualitative and quantitative biological information regarding water diffusivity in a non-invasive manner. The apparent diffusion coefficient (ADC) measures water mobility and can be quantified from the signal intensity loss between two or more b-values. Different studies reported that ADC values are directly associated with microvessel density and cellularity. One of the main aspects that is in discussion is the b-values that must be used in the DWI sequence in order to compute ADC.
- Analyses of pharyngeal constrictor muscles doses in radiotherapy of head and neck cancer patientsPublication . Guerra, Jéssica; Khouri, Leila; Ferreira, BrigidaLate dysphagia is a radiotherapy (RT) side-effect that may develop up to 3 years after treatment and could be related to the irradiation of the Pharyngeal Constrictor Muscles (PCM) in RT. To quantify the radiation dose delivered to the PCM in head and neck (H&N) cancer patients with and without dysphagia.
- Analysis of the cochlear dose in head and neck cancer radiotherapyPublication . Afonso, Jennifer; Khouri, Leila; Ferreira, BrigidaInternal hearing damage induced by radiotherapy (RT) can lead to sensorineural hearing loss (hypoacusia) due tumor’s proximity with the auditory apparatus. Furthermore, the concurrent use of RT with chemotherapy (cisplatin) is known to increase toxicity. To quantify the radiation dose delivered to the (ipsilateral and contralateral) cochlea in head and neck cancer patients with and without hypoacusia.
- A derivative-free multistart framework for an automated noncoplanar beam angle optimization in IMRTPublication . Rocha, Humberto; Dias, Joana; Ventura, Tiago; BC Ferreira; Lopes, Maria do CarmoThe inverse planning of an intensity-modulated radiation therapy (IMRT) treatment requires decisions regarding the angles used for radiation incidence, even when arcs are used. The possibility of improving the quality of treatment plans by an optimized selection of the beam angle incidences-beam angle optimization (BAO)-is seldom done in clinical practice. The inclusion of noncoplanar beam incidences in an automated optimization routine is even more unusual. However, for some tumor sites, the advantage of considering noncoplanar beam incidences is well known. This paper presents the benefits of using a derivative-free multistart framework for the optimization of the noncoplanar BAO problem.