Percorrer por autor "Oliveira, Susana"
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- Alternative regimens for treating prostate cancer using equivalent uniform dose and Monte Carlo methodsPublication . Oliveira, Susana; Rosmanets, Yuriy; Teles, Pedro; Fernandes, Lisete; Teixeira, Nuno; Vaz, PedroIntroduction - Conventional radiotherapy treatments are administrated with 2 Gy external beam radiotherapy (EBRT) fractions. It has been postulated that prostate cancer would respond to radiotherapy as a slowly proliferating late-responding normal tissue, benefiting from hypo-fractionated regimens. Highly conformed brachytherapy is a treatment option either alone or combined with EBRT. Purpose - To identify alternative radiotherapy regimens for treating prostate cancer using EBRT and low dose-rate brachytherapy (LDRBT) with 125I implants, biologically equivalent to conventional treatments in terms of uniform equivalent dose (EUD). Materials and methods - The EUD concept was used, together with Monte Carlo (MC) methods. Two voxel phantoms were segmented from the computed tomography of patients to obtain the energy deposition derived from the MC simulations of EBRT and LDRBT treatments on a voxel-by-voxel basis. The energy deposition was converted in EUD. Equivalent regimens to EUDs of 72 Gy, 80 Gy, 90 Gy, and 100 Gy were determined for increasing fractions of 1.8–5.0 Gy and amounts of LDRBT from 0 Gy (EBRT exclusive) to 145 Gy. The resulting EUD for rectum was also evaluated. Results - Alternative schemes equivalent, in terms of EUD, were obtained. For example, it is equivalent to an EUD of 72 Gy, 38 × 2 Gy, 20 × 3 Gy or 9 × 5 Gy of EBRT, or 6 × 5 Gy of EBRT plus 50 Gy of LDRBT. The rectum benefits of higher amounts of LDRBT for EBRT fractionations <2.5 Gy and larger fractions for LDRBT dose <50 Gy. Conclusion - Alternative regimens for the treatment of prostate cancer with EBRT and LDRBT are proposed. The rational for the use of brachytherapy becomes less relevant with the increasing therapeutic ratio achieved with hypo-fractionated EBRT.
- Controlo da qualidade dosimétrico no serviço de radioterapia do Hospital CUF Descobertas (HCD): importância do controlo da qualidade do sector da física e resultados da auditoria ESTRO-EQUALPublication . Jacob, Katia; Rosa, Maria João; Ferreira, Paulo; Oliveira, Susana; Sousa, Mónica; Fernandes, Paulo; Parafita, R.; Teixeira, Nuno; Ramalho, Miguel; Rodrigues, RuiA calibração e o controlo da qualidade de um acelerador linear são passos muito importantes num serviço de Radioterapia, para garantir a qualidade dos tratamentos prestados. O sector da Física da Unidade de Radioterapia do Hospital Cuf Descobertas implementou um rigoroso Programa de controlo de qualidade ao equipamento produtor de radiação e aos equipamentos medidores de radiação, de acordo com o Dec-Lei 180/2002 e com os protocolos internacionais. Para tal, foram implementados procedimentos, criadas folhas de cálculo, instruções de trabalho e impressos. Foram ainda implementados testes aos equipamentos com periodicidade definida: controlo de qualidade diário e controlo de qualidade após intervenções (manutenções preventivas e correctivas). No decorrer do ano de 2005, o sector da Física colaborou activamente com toda a equipa da Radioterapia na implementação da Norma ISO 9001:2000 no serviço, contribuindo com o seu know how na implementação desta, numa área tão importante como a da garantia da qualidade dos feixes de radiação e das respectivas calibrações em dose. Numa procura de melhoria contínua da qualidade dos serviços prestados aos pacientes, decorre ainda uma auditoria externa da EQUAL-ESTRO*, intercomparação postal com dosímetros termoluminescentes. A qualidade dos feixes de energias utilizados diariamente é analisada, tanto ao nível das calibrações absolutas de cada um dos feixes de fotões e de electrões, como ao nível dos cálculos de dose obtidos com o sistema de planimetria XiO da CMS. Os resultados das duas primeiras fases da intercomparação, relativa aos dois feixes de fotões de 6 MV e 15 MV e feixes de electrões de 4 MeV, 8 MeV e 12 MeV, foram considerados pela EQUAL-ESTRO num nível óptimo (desvio máximo na dose medida em relação à dose de referência |d| ≤ 3%).
- Dietary synergy of chub mackerel and quinoa in reducing cognitive decline and retinal degeneration in the 5XFAD Alzheimer's mouse modelPublication . Gomes-Bispo, Ana; Mello-Sampayo, Cristina; Camacho, Pedro; Rego, Beatriz; Carvalho, Sandra; Lopes, Paula A.; Gomes, Romina; Oliveira, Susana; Lourenço, Maria; Pinto, Rui; Motta, Carla; Correia, Jorge; Afonso, Cláudia; Cardoso, Carlos; Bandarra, Narcisa M.; Prates, José A. M.Alzheimer's disease (AD) is marked by cognitive decline and retinal degeneration. This study aimed to explore the potential of dietary chub mackerel (Scomber colias), rich in docosahexaenoic acid (DHA) and vitamin B12, and quinoa, a source of vitamin B9, to prevent or delay these effects in a 5XFAD mouse model of AD. Thirty-two five-week-old male mice were divided into four groups: control, 10% chub mackerel, 5% quinoa, and 10% chub mackerel plus 5% quinoa, over 28 weeks. After 28 weeks, behavioural tests confirmed that none of the tested diets induced confounding effects related to anxiety-like behaviour or motor impairment. The diet combining chub mackerel and quinoa improved selected memory-associated outcomes and protected retinal integrity (p < 0.05), particularly within the neural layers. This diet also improved the brain n-3/n-6 PUFA ratio, primarily by reducing n-6 PUFA levels rather than by a significant increase in DHA. These benefits likely result from the complementary effects of key nutrients, including DHA and vitamins B9 and B12. The preservation of retinal thickness observed with the combined diet supports the use of retinal layer assessment as a potential non-invasive readout of AD-associated neurodegeneration. These findings indicate that combining chub mackerel and quinoa may help mitigate selected neurodegenerative and retinal alterations in the 5XFAD model, positioning them as promising components of a dietary strategy to support neuroprotection and retinal health during AD-related decline.