Browsing by Author "Ferreira, P."
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- Dosimetric considerations from 200 prostate brachytherapy treatments with 1251 according to the real-time planning methodPublication . Teixeira, Nuno; Campos, L.; Carvoeiras, P.; Cunha, Gilda; Varregoso, J.; Valsassina, R.; Pontes, M.; Galhos, R.; Ferreira, P.; Justo, U.Prostate brachytherapy with radioactive seeds is one of the options for prostate cancer treatment. Some dosimetric methods may be used, from the pre-planning to the realtime planning. This study covers 200 patients treated with 12sI radioactive seeds, for a period of time of 4 years. The software used is VariSeed. According to the real-time planning method, the dosimetry is done inside the operating room. The ultrasound probe is inside the rectum of the patient during all the treatment time, and images of the prostate, urethra and rectum are obtained by ultrasound technique. The dosimetry is on realtime, and the source positions in the TPS are exactly the same of the positions inside the prostate. With this technique one may have the values of very important parameters, like Dgo Dgs Vgo Dloo and Vlso for prostate. After one month the patient is submitted to a CT exam, and a new dosimetry is performed, being the contouring done over the new C-I images. With this new dosimetry one may calculate the same parameters already calculated for the real-time planning dosimetry. In this work authors present a statistical analysis (table 1) of the main parameters, obtained either duringthe pre-planning dosimetry or from the CT, and show some very interesting results and conclusions.
- Ionometric and fricke electron and gamma dosimetry for the implementation of waste water treatment by radiation in PortugalPublication . Ferreira, P.; Jacob, K.; Rosat, M.; Galhós, R.; Serrai, F.; Oliveira, S.; Teixeira, Nuno; Ramalho, M.Application of radiation as an efficient process to reduce the microbial levels in materials (food, environmental, health care products). Irradiation of organic and inorganic compounds with electron and gamma rays can modify the micro organisms, depending on the energy, dose rate, and others variables related to the irradiation conditions. Anthropogenic sources have been responsible for introducing high levels of chemical elements and compounds into the environment, many of this through the industrial waste waters. This is an issue of global concern, with potential impact on human health and the environment. IAEA recognizes the potentiality of radiation technology to clean up waste discharges, and since 2003 IAEA participate in this project. Although this is a multidisciplinary project, by the physical point of view the main objective is to characterize the most efficient electron (by intercomparison with gamma) beam, obtaining the better irradiation geometry, to implement waste water (originated in hospitals, food industry ...) treatments. Until now, we've characterized electron beams with Ionometric and fricke dosimetry at non-standard irradiation conditions, in commercial Linacs for radiotherapy purposes. We used a Varian Clinac 2100 CD, with the special TBI ETRAY conditions and nominal dose rate of 1000 UM/min, and an Elekta Digital Precise with nominal dose rate of 400 UM/min. The better dose rates obtained in water were approximately equal to 1.4 kGy/h and 0.7 kGy/h, respectively. The impact of the radiation has been studied microbiologically, toxicologically and chemically, and the evaluation between this kind of radiation and cobalt gamma radiation is also carried out at the same time. The results obtained until know and the continuous support of the IAEA experts in the project, indicates that this project will contribute to a better quality of the Portuguese industrial or hospital complexes, minimising the impact of pollutants on the environment.