Papers by Eduardo de Paiva
DOAJ (DOAJ: Directory of Open Access Journals), Jul 1, 2018
Journal of Physics G, Jun 1, 2001
Journal of Physics G, Sep 1, 1999
Quasi-monochromatic photon beams of 108 MeV Compton-edge energy produced in the ROKK-1M facility ... more Quasi-monochromatic photon beams of 108 MeV Compton-edge energy produced in the ROKK-1M facility at the storage ring VEPP-4M (BINP, Novosibirsk) and makrofol sheets as fission track detectors were used to measure the photofission yield of 27 Al. The fission yield was found to be (160 ± 55) µb. From this result and previously measured 27 Al photofission yield at ∼79 MeV end-point energy with the LADON apparatus, the trends of fission cross section and fissility have been obtained in the incident photon energy range ∼40-110 MeV. The present results and data for other intermediate-mass nuclei obtained with the same methodology indicate an increase of fissility with decreasing Z 2 /A as predicted by the liquid drop model for fissioning systems lighter than ∼Ag.
INTERNATIONAL JOURNAL OF MEDICAL SCIENCE AND CLINICAL RESEARCH STUDIES
Due to its short range in tissue and high dose gradient beta radiation may be used to the therapy... more Due to its short range in tissue and high dose gradient beta radiation may be used to the therapy of small and superficial skin lesions. In this short study a conceptual design of a novel multi-hexagonal beta applicator loaded with Yttrium-90 is presented. Calculations of dose rates around the applicator area performed using the beta-point source dose function formalism and initial results show that over 90\% of the beta radiation energy from the multi-hexagonal applicator loaded with Yttrium-90 is absorbed in the first layers of the skin tissue. Results show that the multi-hexagonal beta applicator has the potential to be used in the brachytherapy treatment of non-melanoma skin cancers.
Radiation Protection Dosimetry, 2008
Data related to 11 y of high-energy photon radiotherapy beam dosimetry are presented and analysed... more Data related to 11 y of high-energy photon radiotherapy beam dosimetry are presented and analysed. Dosimetric evaluations were carried out using water phantoms and thimble ionisation chambers and are part of the radiation protection regulatory licensing process for medicine facilities of Brazilian government. Measurements were done at reference conditions for a standard absorbed dose of 100 cGy [cGy (=1 rad)]. The absolute per cent deviation between the measured and presumed delivered doses should not exceed the tolerance level of +/-3%. The first dosimetry survey from 1996 to 1998 showed a situation that was an object of concern. Deviations of 22 and 18.7% could be measured, although small deviations were also obtained. After 1998, the improvement in dosimetry quality control by the radiotherapy centres became clear, with most of the deviations situated within the +/-3% range. The decrease in the measured deviations presents the effective success of the Institute of Radiation Protection and Dosimetry audit programme for the improvement in the control of radiotherapy photon beams in Rio de Janeiro. Also, it is possible to recommend to Brazilian regulatory organisation a decrease in the tolerance level for dosimetric deviations in order to achieve a more precise dose delivered to patients in radiotherapy centres.
Radiation Protection Dosimetry, 2009
The Brazilian national regulatory authority, National Commission of Nuclear Energy, requires that... more The Brazilian national regulatory authority, National Commission of Nuclear Energy, requires that dose rates in the vicinity of teletherapy treatment rooms do not exceed the permissible limits for workers as well as members of the public, depending on the place considered. At the end of 2005, the Brazilian national regulatory authority reduced the permissible dose limit for controlled areas from 1000 to 400 microSv week(-1). Therefore, the aim of this work is to verify the adequacy of structural shielding to this new limit for telecobalt units that had their sources changed and clinic linear accelerators (ALs) installed before the end of 2005. Considering the ALs, measurements of dose rates in controlled areas did not exceed the new permissible limit, excepting for a single case. In the case of (60)Co units, a similar situation is observed for controlled areas, although several non-conformities to the limit of uncontrolled area could be observed.
Journal of Physics G: Nuclear and Particle Physics, 1998
Journal of Physics G: Nuclear and Particle Physics, 1993
ABSTRACT A study of photofission on natTa, natW and natPt nuclei induced by monochromatic photons... more ABSTRACT A study of photofission on natTa, natW and natPt nuclei induced by monochromatic photons of 69 MeV has been performed. The fission yields have been measured by using makrofoil sheets as fission-track detectors, in thick-target 2 pi geometry. The absolute photofission cross sections for the tantalum, tungsten and platinum targets are found, respectively, to be 4.8+or-1.0 mu b, 5.2+or-1.2 mu b and 10+or-2 mu b, and the corresponding deduced fissilities are (3.2+or-0.7)*10-4, (3.4+or-0.8)*10-4 and (6.4+or-1.3)*104-4.
Journal of Physics G: Nuclear and Particle Physics, 1996
Journal of Physics G: Nuclear and Particle Physics, 2002
The European Physical Journal Plus
Revista de Matemática, Jul 25, 2019
STUDIES IN HEALTH SCIENCES
High-energy photons produced by large medical linear accelerators are widely used in medicine for... more High-energy photons produced by large medical linear accelerators are widely used in medicine for the treatment of various types of malignant tumors. In the last decades the use of photon beams in radiation therapy was improved due to the arising of advanced technologies and techniques of treatment such as IMRT (intensity modulated radiation therapy), VMAT (volumetric modulated arc therapy), IGRT (image guided radiotherapy) and SBRT (stereotactic body radiation therapy). However, we should guarantee that the use of these procedures does not increase the radiation doses in the vicinities of the radiotherapy room above the permissible level. In this work we carry out an estimation of cost of concrete shielding for a standard radiotherapy room and for photon energies ranging from 4 to 30 MeV (megaelectron volts), and always considering the constraint of the allowed level of radiation in the vicinity of the room. Results have indicated that total cost of concrete increases about 22-25% ...
STUDIES IN HEALTH SCIENCES
Ionizing radiations have an important role in medicine in the treatment of various types of cance... more Ionizing radiations have an important role in medicine in the treatment of various types of cancer. In particular high-energy photon beams associated with advanced techniques such as IMRT (intensity modulated radiation therapy) and VMAT (volumetric modulated arc therapy) have been largely used in external beam radiotherapy. However, the use of these techniques requires a special attention to the shielding of the walls of the facility room housing a linear accelerator that produces high-energy photon beams. In this study we performed an estimation of cost of concrete shielding to a radiotherapy room where patients are treated with photon beams of energies from 4 to 30 MeV (mega-electron volts) based on simple assumptions. Results have shown that total cost of concrete increases about 19% when photon energies increase from 4 to 30 MeV for conventional therapy and about 23% when modern techniques are included. Results have also indicated a linear increasing of costs with the area of th...
Experiências em Ensino de Ciências, 2016
No Brasil é adotado o Sistema Internacional de Unidades (SI), que define as grandezas e unidades ... more No Brasil é adotado o Sistema Internacional de Unidades (SI), que define as grandezas e unidades de base e estabelece as regras para seu uso. Contudo, em produtos comumente encontrados no cotidiano podem ser observados vários erros na grafia de seus nomes e símbolos. O objetivo desta breve nota é estender o trabalho da sala de aula pelo uso de conceitos básicos aplicados a um problema de relevância prática do cotidiano, que é o correto uso das unidades em que as grandezas são expressas. Nesta tentativa, são mostrados exemplos de erros em vez de acertos no uso de símbolos e unidades e conceitos simples de física em nível de ensino médio são suficientes.
STUDIES IN HEALTH SCIENCES, 2022
A radioterapia com o uso de feixes de fótons produzidos por aceleradores lineares experimentou im... more A radioterapia com o uso de feixes de fótons produzidos por aceleradores lineares experimentou importantes avanços tecnológicos nas últimas décadas, contribuindo para melhorar a qualidade do tratamento de pacientes com câncer. Neste sentido, a aprendizagem com incidentes ganhou grande destaque durante sucessivas abordagens sobre a segurança do paciente, resultando na criação de ferramentas voltadas para essa finalidade. No Brasil, ainda existem poucos estudos realizados sobre essa abordagem na radioterapia e, diante do crescimento da oncologia no país e do aumento constante das estimativas de novos casos, foi observada a necessidade da criação de um sistema de registro e aprendizagem com incidentes a fim de promover melhorias no atendimento, eficácia no tratamento e proporcionar aprimoramento dos profissionais. Neste trabalho apresentamos o desenvolvimento de uma ferramenta para registro e análise de incidentes que seja voltada para a realidade do país. Foram realizadas etapas que e...
Trends Journal of Sciences Research, 2019
The number of cases of cancer has significantly increased in the world and the use of ionizing ra... more The number of cases of cancer has significantly increased in the world and the use of ionizing radiation produced by large clinical linear accelerators plays an important role in the treatment of tumors. Although radiotherapy is considered a safe medical practice, it may bring some risks for the patient and in some extreme cases even her/his death. Over the last decades, the learning with incidents there has been a powerful way to prevent them to turn to happen. In this work a digital tool was developed for recording and evaluation of incidents in external beam radiation therapy. The tool was designed to function in an intranet environment, but it can also be used in the offline mode and is based on a set of sequential forms filled by the user (e.g. medical physicists, medical dosimetrists, radiation oncologists, radiotherapy technicians). The software was firstly applied in a radiation oncology department of a public Institution in Rio de Janeiro, Brazil. The software has proved to be an important and promising tool to improve the healthcare quality of patients undergoing radiation therapy.
Journal of Applied Clinical Medical Physics, Jan 30, 2011
The Brazilian Institute of Radiation Protection and Dosimetry (IRD/CNEN) carried out quality assu... more The Brazilian Institute of Radiation Protection and Dosimetry (IRD/CNEN) carried out quality assurance regulatory audits in Brazilian radiotherapy facilities from 1995 to 2007. In this work, the set of data collected from 195 radiotherapy facilities that use high-energy photon beams are analyzed. They include results from audits in linear electron accelerators and/or Co-60 units. The inspectors of IRD/CNEN performed the dosimetry of high-energy radiotherapy photon beams according to the IAEA dosimetry protocols TRS 277 and TRS 398, and the values of measurements were compared to stated values. Other aspects of radiological protection were checked during on-site audits such as calibration certification of clinical dosimeters and portable monitors, existence and use of check source, use of barometer and thermometer, individual dose registry and training of staff. It was verified that no check source was available in 38% of the visited facilities; the training of personnel was not adeq...
Cultura, epistemologia e educação em ciências exatas e da terra
Scientia Plena, 2014
Beta-particle sources can be used in radiotherapy to treat several diseases. In particular cylind... more Beta-particle sources can be used in radiotherapy to treat several diseases. In particular cylindrical (seed) beta-minus sources have been used in cardiology for the prevention of restenosis of coronary artery. Two radioisotopes suitable to be used in intravascular brachytherapy treatment of arteries are the pure beta-emitters 32 P and 90 Y. In this work a routine calculation to estimate absorbed dose rate distributions around cylindrical sources containing the beta emitters 32 P and 90 Y has been developed in order to handle with various configurations of radii, lengths and distances in a faster and simple way. The results of relative dose rates are compared with published dose distributions for 32 P and 90 Sr/ 90 Y sources using the Monte Carlo method and a good agreement (differences < 6 %) has been found in the region of clinical interest measured from the cylindrical source center.
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Papers by Eduardo de Paiva