LUCIO PEREIRA NEVES
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Artigo IPEN-doc 23524 Estimate of S-values for children due to six positron emitting radionuclides used in PET examinations2017 - BELINATO, WALMIR; SANTOS, WILLIAM S.; PERINI, ANA P.; NEVES, LUCIO P.; CALDAS, LINDA V.E.; SOUZA, DIVANIZIA N.Positron emission tomography (PET) has revolutionized the diagnosis of cancer since its conception. When combined with computed tomography (CT), PET/CT performed in children produces highly accurate diagnoses from images of regions affected by malignant tumors. Considering the high risk to children when exposed to ionizing radiation, a dosimetric study for PET/CT procedures is necessary. Specific absorbed fractions (SAF) were determined for monoenergetic photons and positrons, as well as the S-values for six positron emitting radionuclides (11C, 13N, 18F, 68Ga, 82Rb, 15O), and 22 source organs. The study was performed for six pediatric anthropomorphic hybrid models, including the newborn and 1 year hermaphrodite, 5 and 10-year-old male and female, using the Monte Carlo N-Particle eXtended code (MCNPX, version 2.7.0). The results of the SAF in source organs and S-values for all organs showed to be inversely related to the age of the phantoms, which includes the variation of body weight. The results also showed that radionuclides with higher energy peak emission produces larger auto absorbed S-values due to local dose deposition by positron decay. The S-values for the source organs are considerably larger due to the interaction of tissue with non-penetrating particles (electrons and positrons) and present a linear relationship with the phantom body masses. The results of the Svalues determined for positron-emitting radionuclides can be used to assess the radiation dose delivered to pediatric patients subjected to PET examination in clinical settings. The novelty of this work is associated with the determination of auto absorbed S-values, in six new pediatric virtual anthropomorphic phantoms, for six emitting positrons, commonly employed in PET exams.Artigo IPEN-doc 21281 Evaluation of the medical and occupational shielding in cerebral angiography using Monte Carlo simulation and virtual anthropomorphic phantoms2015 - SANTOS, WILLIAM S.; NEVES, LUCIO P.; PERINI, ANA P.; CALDAS, LINDA V.E.; MAIA, ANA F.Artigo IPEN-doc 20265 Development and characterization of a graphite-walled ionization chamber as a reference dosimeter for sup(60)Co beams2014 - PERINI, ANA P.; NEVES, LUCIO P.; CALDAS, LINDA V.E.Artigo IPEN-doc 20263 Dosimetric study of a brachytherapy treatment of esophagus with Brazilian sup(192)Ir sources using an anthropomorphic phantom2014 - NEVES, LUCIO P.; SANTOS, WILLIAM S.; GORSKI, RONAN; PERINI, ANA P.; MAIA, ANA F.; CALDAS, LINDA V.E.; ORENGO, GILBERTOSeveral radioisotopes are produced at Instituto de Pesquisas Energéticas e Nucleares for the use in medical treatments, including the activation of 192Ir sources. These sources are suitable for brachytherapy treatments, due to their low or high activity, depending on the concentration of 192Ir, easiness to manufacture, small size, stable daughter products and the possibility of re-utilization. They may be used for the treatment of prostate, cervix, head and neck, skin, breast, gallbladder, uterus, vagina, lung, rectum, and eye cancer treatment. In this work, the use of some 192Ir sources was studied for the treatment of esophagus cancer, especially the dose determination of important structures, such as those on the mediastinum. This was carried out utilizing a FASH anthropomorphic phantom and the MCNP5 Monte Carlo code to transport the radiation through matter. It was possible to observe that the doses at lungs, breast, esophagus, thyroid and heart were the highest, which was expected due to their proximity to the source. Therefore, the data are useful to assess the representative dose specific to brachytherapy treatments on the esophagus for radiation protection purposes.Artigo IPEN-doc 20240 A new standard cylindrical graphite-walled ionization chamber for dosimetry in sup(90)Co beams at calibration laboratories2014 - NEVES, LUCIO P.; PERINI, ANA P.; CALDAS, LINDA V.E.Artigo IPEN-doc 19966 A new parallel-plate graphite ionization chamber as a sup(60)Co gamma radiation reference instrument2014 - PERINI, ANA P.; NEVES, LUCIO P.; FERNANDEZ VAREA, JOSÉ M.; CASSOLA, VAGNER F.; KRAMER, RICHARD; KHOURY, HELEN J.; CALDAS, LINDA V.E.Artigo IPEN-doc 19963 Dosimetric application of a special pencil ionization chamber in radiotherapy x-ray beams2014 - NEVES, LUCIO P.; PERINI, ANA P.; FERNANDEZ VAREA, JOSÉ M.; CASSOLA, VAGNER F.; KRAMER, RICHARD; KHOURY, HELEN J.; CALDAS, LINDA V.E.The aim of this work was to study the performance of a pencil ionization chamber with a sensitive volume of only 1.06 cm3 and a length of 3.0 cm, developed at the Calibration Laboratory of the IPEN, in very low-energy radiotherapy X-ray beams. These beams are still used for certain skin cancer treatments due to their rapid attenuation in tissue. The dosimeter performance was evaluated in some tests proposed by the IEC 60731 standard: short- and long-term stability and linearity of response. For a complete analysis of the dosimeter response, the EGSnrc Monte Carlo simulation was utilized to investigate the influence of its different parts on the ionization chamber response. All results of the tests were in accordance with the recommended limits, and this work shows that it is possible to extend the application of this pencil-type ionization chamber developed at the LCI.Artigo IPEN-doc 18287 Characterization of an extrapolation chamber for low-energy x-rays: Experimentakl and Monte Carlo preliminary results2012 - NEVES, LUCIO P.; SILVA, ERIC A.B.; PERINI, ANA P.; MAIDANA, NORA L.; CALDAS, LINDA V.E.Artigo IPEN-doc 18288 Evaluation of the voltage quantities measured with different noninvasive meter for quality control at a calibration laboratory2012 - VIVOLO, VITOR; NEVES, LUCIO P.; PERINI, ANA P.; SILVA, JONAS O.; LUCENA, RODRIGO F.; POTIENS, MARIA da P.A.; CALDAS, LINDA V.E.Artigo IPEN-doc 18290 Characterization of a CT ionization chamber for radiation field mapping2012 - PERINI, ANA P.; NEVES, LUCIO P.; VIVOLO, VITOR; XAVIER, MARCOS; KHOURY, HELEN J.; CALDAS, LINDA V.E.