Papers by Francisco Doblado
Radiotherapy and Oncology, 2005
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Medical Physics, 2007
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Medical Physics, 2004
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International Journal of Radiation Oncology*Biology*Physics, 2003
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International Journal of Radiation Oncology*Biology*Physics, 2007
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Journal of Applied Clinical Medical Physics, 2014
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Radiotherapy and Oncology
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Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), Jan 6, 2017
Biological treatment plan evaluation does not currently consider second cancer induction from per... more Biological treatment plan evaluation does not currently consider second cancer induction from peripheral doses associated to photon radiotherapy. The aim is to propose a methodology to characterize the therapeutic window by means of an integral radiobiological approach, which considers not only Tumour Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) but also Secondary Cancer Probability (SCP). Uncomplicated and Cancer-Free Control Probability (UCFCP) function has been proposed assuming a statistically uncorrelated response for tumour and normal tissues. The Poisson's and Lyman's models were chosen for TCP and NTCP calculations, respectively. SCP was modelled as the summation of risks associated to photon and neutron irradiation of radiosensitive organs. For the medium (>4Gy) and low dose regions, mechanistic and linear secondary cancer risks models were used, respectively. Two conformal and intensity-modulated prostate plans at 15MV (same prescr...
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Physica Medica, 2017
Neutron peripheral contamination in high-energy radiotherapy implies an increase of secondary rad... more Neutron peripheral contamination in high-energy radiotherapy implies an increase of secondary radiation-induced cancer risk. Although peripheral neutron dose (PND) has been evaluated in organs, few studies have been performed regarding patient size. This work aims to improve an existing methodology for adult patient PND estimations to generalize it to young and children, for its implementation in treatment planning systems (TPS). As a first step, we aimed to generalize the previous model to be usable with any thermal neutron detector. Then, taking into account total neutron spectra and dose-to-point thermal neutron fluence measurements for three phantom sizes (adult, teen and child) and two common treatment locations (H&N and abdomen), the new model was proposed. It represents an upgraded parameterization and extension of the existing one, including patient anatomy. Finally, comparison between estimations and measurements, as well as validation against the original model, was carried out for 510 measured patients. Concordance found between experimental and theoretical estimations makes us confident about later implementation in treatment planning systems. Comparison among the previous and upgraded models shows no significant differences for the adult case. However, an important underestimation (34.1% on average) can be observed regarding child case for the original one. An improved generalization of an existing PND model, considering patient anatomy has been validated and used in real patients. The final methodology is easily implementable in clinical routine and TPS thanks to the ready availability of input parameters (patient height and weight, high-energy MU and facility characterization).
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Los haces de radiacion de altas energias ( 10 MEV) estan generalmente contaminados con neutrones ... more Los haces de radiacion de altas energias ( 10 MEV) estan generalmente contaminados con neutrones resultantes de la reaccion (y n) producida por la interaccion de los fotones con los elementos constituyentes del acelerador (blanco blindaje colimadores bobinas de deviacion...). Si bien el exceso de dosis anadido al paciente por la presencia de esta particula puede ser despreciable no ocurre igual desde el punto de vista de la proteccion radiologica del personal ya que aparecen nuevos isotopos debido al fenomeno de la activacion de los diferentes materiales presentes en la sala de tratamientos. En este trabajo se ha valorado el flujo de neutrones existente en diferentes puntos del bunker en torno a nuestro acelerador saturno-20. La valoracion ha sido realizada mediante la activacion de chapas de indio y posterior lectura en un analizador multicanal. La energia nominal utilizada es de rx-18MV por ser la que produce mayor flujo de neutrones de los haces disponibles. Asi mismo mediante el procedimiento teorico del metodo de Montecarlo hemos obtenido el espectro neutronico junto al acelerador. Por ultimo una dosimetria ambiental de la sala nos ha permitido valorar el riesgo radiologico que supone este fenomeno para el personal profesionalmente expuesto.
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Alfa, 2014
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IFMBE Proceedings, 2015
A new thermal neutron detector (TNRD), developed for nuclear research, has shown to be effective ... more A new thermal neutron detector (TNRD), developed for nuclear research, has shown to be effective for clinical use in peripheral neutron dose estimation, either in patient and ‘in-phantom’ measurements. This work shows some TNRD difficulties when adapting it to radiotherapy environments, mainly due to the fact that it has shown structural limitations. Two problems have been studied: (1) the influence of cable lengthening, necessary to be operative in a radiotherapy environment and (2) cable irradiation during the measurements. As we are measuring very small signals, we have to take into account not only these two facts but also the quality of the materials and connectors used. Thus, we studied cable elongation and irradiation influences in conventional and extreme situations once the setup was improved, in order to avoid uncertainties which could be of the order of the signal. Mean deviations of -0.15% from the original TNRD cable extension have been noticed. For the wide variety of conditions tested, in terms of both dose delivered and setup of the radiotherapy exposure, uncertainties smaller than 1.2% have been estimated.
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Radiotherapy and Oncology, 2015
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Radiotherapy and Oncology, 2015
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Radiotherapy and Oncology, 2014
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IFMBE Proceedings, 2013
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Papers by Francisco Doblado