Navegação Eventos - Artigos por assunto "absorbed radiation doses"

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  • IPEN-DOC 19438

    OCAMPO, IVETTE Z.; OKAZAKI, KAYO ; VIEIRA, DANIEL P.. An improved in vitro micronucleus assay to biological dosimetry. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE; MEETING ON NUCLEAR APPLICATIONS, 11th; MEETING ON REACTOR PHYSICS AND THERMAL HYDRAULICS, 18th; MEETING ON NUCLEAR INDUSTRY, 3rd, November 24-29, 2013, Recife, PE. Proceedings... Sao Paulo: ABEN, 2013, 2013.

    Palavras-Chave: absorbed radiation doses; biological radiation effects; chromosomal aberrations; cobalt 60; dna; fluorescence; in vitro; ionizing radiations; microscopy; nitric oxide; tumor cells

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  • IPEN-DOC 26284

    ALENCAR, CATARINE S.L. ; PAIVA, ANA R.N. ; SILVA, LEONARDO G. de A. e ; SOMESSARI, ELIZABETH S.R. ; VAZ, JORGE M. ; SPINACE, ESTEVAM V. . AuCu/TiO2 catalysts prepared using electron beam irradiation for the preferential oxidation of carbono monoxide in hydrogen-rich mixtures. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2481-2491.

    Abstract: The major part of the world production of hydrogen is originated from a combination of methane steam reforming and water gas shift reaction resulting in a n H 2 rich mixture known as reformate gas, which contains about 1% vol (10, 000 p pm) of carbon monoxide (CO). The preferential oxidation reaction of CO in H 2 rich mixtures (CO PROX) has been considered a very promising process for H 2 purification, reducing CO for values below 50 ppm allowing its use in Proton Exchange Membrane Fuel Cells (PEMFC). Au nanopart icles supported on TiO 2 (Au/TiO 2 ) catalysts have been shown good activity and selectivity for CO PROX reaction in the temperature range between 20 ºC and 80 ºC; however, the catalytic activity strongly depend s on the preparation method. Also, the addition of Cu to the Au/TiO 2 catalyst could increase the activity and selectivity for CO PROX reaction. In this work, AuCu/TiO 2 catalysts with composition 0.5%Au0. 5%Cu/TiO 2 were prepared in a single step using electron beam irradiation, where the Au 3+ and Cu 2+ ion s were dissolved in water/2 propanol solution , the TiO 2 support was dispersed and the obtained mixture was irradiated under stirring at room temperature using different dose rates ( 8 64 kGy s 1 ) and doses 144 576 kGy The catalysts were characterized by energy dispersive X ray analysis (EDX), X ray diffraction (XRD), transmissi on electron microscopy (TEM), temperature programmed reduction (TPR) and tested for CO PROX reaction In the studied conditions, it was observed that the increase of t he dose rate and the total dose contributed to a decrease in the mean nanoparticle sizes. The best result was obtained with a catalyst prepared with a dose rate of 64 kGy s 1 and a dose of 576 kGy showed a CO conversion of 45% and a CO 2 selectivity of 30% at 150 o C.

    Palavras-Chave: absorbed radiation doses; carbon monoxide; catalysts; copper; dose rates; electron beams; gold; hydrogen; irradiation; mixtures; nanoparticles; oxidation; titanium oxides; transmission electron microscopy; x-ray diffraction; x-ray spectroscopy

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  • IPEN-DOC 24629

    BELINATO, WALMIR; SANTOS, WILLIAM S.; PERINI, ANA P.; NEVES, LUCIO P.; CALDAS, LINDA V.E. ; SOUZA, DIVANIZA N.. Avaliação de doses equivalentes em PET/CT com 18F utilizando o Método Monte Carlo com código MCNPX. In: ANAIS DA SOCIEDADE BRASILEIRA DE BIOCIENCIAS NUCLEARES, 09-11 de outubro, 2017, São Paulo, SP. Anais... Rio de Janeiro, RJ: Sociedade Brasileira de Biociências Nucleares, 2017. p. 60-73.

    Abstract: A técnica diagnóstica PET/CT (Positron Emisson Tomography/Computer Tomography) une recursos diagnósticos da Medicina Nuclear e da Radiologia. A técnica PET produz imagens metabólicas por meio de radiofármacos emissores de pósitrons. O presente trabalho usou o método Monte Carlo (MMC), especificamente o código de Monte Carlo NParticle – MCNPX, para simular a interação da radiação envolvendo fótons e partículas, tais como pósitrons e elétrons, com simuladores antropomórficos adultos virtuais em exames de PET/CT e determinar doses absorvidas e equivalentes em exames de pacientes adultos masculino e feminino. Para os cálculos, considerou-se os parâmetros dos feixes de tomografia computadorizada (colimação e filtração) de dois equipamentos distintos e as atividades de 18F-FDG comumente empregadas em exames de rotina. Foram estimados novos valores para fatores de conversão de dose absorvida por atividade administrada (valores-S) para doses internas em órgãos de pacientes com características similares aos simuladores de voxels escolhidos. Comparando-se com as doses absorvidas em órgãos devido ao 18F (doses internas), as doses absorvidas médias externas - devido ao feixe de raios X de CT - equivalem a 14,2% (equipamento GE) e 26,3% (equipamento Siemens). Essa diferença entre equipamentos pode ser relacionada principalmente com a quantidade de cortes de CT necessários para o exame de corpo inteiro (40 mm/rotação para ao GE e 20 mm/rotação para o Siemens), com uso do filtro gravata borboleta (filtro bowtie). Considerando-se as doses absorvidas internas, os novos coeficientes por atividade administrada calculados apresentaram um acréscimo próximo de 30% em relação aos valores da ICRP 106 e podem ser associados com representação morfológica mais realista dos órgãos dos simuladores utilizados e à introdução de fatores de espalhamento para fótons, porque os simuladores foram dispostos sobre uma mesa de exames, o que não é levado em consideração na ICRP 106.

    Palavras-Chave: absorbed radiation doses; dosimetry; equivalent radiation doses; fluorine 18; fluorodeoxyglucose; icrp; monte carlo method; phantoms; positron computed tomography; simulators

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  • IPEN-DOC 21092

    CARDOSO, JESSICA R. ; GABRIEL, LEANDRO ; GERALDO, AUREA B.C. ; MOURA, EDUARDO . Characteristics of recycled and electron beam irradiated high density polyethylene samples. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE; MEETING ON NUCLEAR APPLICATIONS, 12th; MEETING ON REACTOR PHYSICS AND THERMAL HYDRAULICS, 19th; MEETING ON NUCLEAR INDUSTRY, 4th, October 4-9, 2015, São Paulo, SP. Proceedings... 2015.

    Palavras-Chave: electron beams; polyethylenes; infrared spectra; cross-linking; absorbed radiation doses; fourier transformation; mechanical properties; mechanical tests; thermal analysis

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  • IPEN-DOC 28193

    AQUINO, SIMONE ; LIMA, JOSE E.A. de; BORRELY, SUELI I. . Combined application of gamma radiation, cleaning and chemical sanitizers in decontamination of vehicle air conditioning filters. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, November 29 - December 2, 2021, Online. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2021.

    Palavras-Chave: vehicles; air conditioners; air conditioning; indoor air pollution; absorbed radiation doses; cryogenics; environmental quality; fungi; heating

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  • IPEN-DOC 24139

    CAMARGO, FABIO de; GONÇALVES, JOSEMARY A.C. ; BUENO, CARMEN C. . A comparison between rad-hard float zone silicon diodes as gamma dosimeter in radiation processing. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: In this work, we report on the results obtained with rad-hard Standard Float Zone (STFZ) and Diffused Oxygenated Float Zone (DOFZ) silicon diodes in radiation processing dosimetry. The dosimetric probes were designed to operate in the direct current mode, as on-line radiation dosimeter. The irradiation of the samples was performed using a 60Co source with a dose rate of almost 2.4 kGy/h. The current response of each diode was measured as a function of the exposure time in steps from 5 kGy up to 50 kGy to achieve a total absorbed dose of 275 kGy. In this dose range it is observed a significant decrease in the photocurrent generated in both devices due to gamma radiation defects produced in their active volumes. To mitigate this effect, the samples were pre-irradiated with 60Co gamma rays at 700 kGy. Despite of being less sensitive, these devices presented stable and reproducible current signals with a relative sensitivity decrease of about 19% within the whole range of dose studied. The dose-response curves of the pre-irradiated diodes showed quadratic behavior with correlation coefficient higher than 0.9999 for total absorbed dose up to 275 kGy. The comparison of the FZ and DOFZ responses evidenced that the latter was slightly superior to the first. However, it is important to note that all pre-irradiated diodes can be used as gamma dosimeters in radiation processing applications.

    Palavras-Chave: absorbed radiation doses; cobalt 60; comparative evaluations; dose rates; gamma dosimetry; oxygen; radiation dose ranges; radiation dose units; silicon diodes; zone melting

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  • IPEN-DOC 26785

    SANTOS, WILLIAM S. ; NEVES, LUCIO P.; PERINI, ANA P.; SANTOS, CARLA J.; BELINATO, WALMIR; SILVA, ROGERIO M.V.; SOARES, MARIA R.; VALERIANO, CAIO C.; CALDAS, LINDA V.E. . Computational modelling of cervix uterus radiation procedure using a virtual anthropomorphic phantom and the MCNPX code. In: CONGRESSO BRASILEIRO DE METROLOGIA, 10.; CONGRESSO INTERNACIONAL DE METROLOGIA ELÉTRICA, 13.; CONGRESSO INTERNACIONAL DE METROLOGIA MECÂNICA, 5.; CONGRESSO BRASILEIRO DE METROLOGIA DAS RADIAÇÕES IONIZANTES, 6.; WORKSHOP DA REDE DE METROLOGIA QUÍMICA DO INMETRO, 4.; CONGRESSO BRASILEIRO DE METROLOGIA ÓPTICA, 3., 24-27 de novembro, 2019, Florianópolis, SC. Anais... Rio de Janeiro, RJ: Sociedade Brasileira de Metrologia, 2019.

    Abstract: There is a serious, and growing, concern about the increased risk of the emergence of a secondary cancer, radio-induced, associated with radiotherapy treatments. To assess the radiation doses to organs outside the target volume, in this work, several computational exposure scenarios were modelled, based on Monte Carlo simulation (MCNPX code). A Varian 2100c accelerator, and a female virtual anthropomorphic phantom were used, in a simulated treatment of cervical cancer. The determination of the dispersed dose would be important for assessing the risk in different organs or tissues. Four treatment fields were applied, varying the gantry angle. It was possible to observe that the conversion factors for equivalent dose were higher for the AP projection. For the RLAT and LLAT projections, the results were similar, fact that may be attributed to the symmetrical distributions of the organs in relation to the radiation source. The results presented in this work showed that the computational exposure scenario provides a versatile and accurate tool to estimate in a ready way the absorbed doses during a cervical treatment.

    Palavras-Chave: absorbed radiation doses; animal tissues; computerized simulation; dosimetry; monte carlo method; organs; phantoms; radiotherapy; uterus

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  • IPEN-DOC 20548

    BARREIRA, JACQUELINE S. ; HUET, SARAH D.P. ; VIVOLO, VITOR . Determination of radiation dose in surcace breast using two types of PMMA simulators. In: INTERNATIONAL NUCLEAR CHEMISTRY CONGRESS, 4th, September 14-19, 2014, Maresias, São Paulo. Proceedings... 2014.

    Palavras-Chave: x radiation; mammary glands; biomedical radiography; radiation detection; absorbed radiation doses; dosimetry; simulators

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  • IPEN-DOC 24184

    OLIVEIRA, M.J.A. ; VASQUEZ, P.A.S. ; ALCANTARA, M.T.S. ; MUNHOZ, M.M.L. ; LUGAO, A.B. . Effect of gamma radiation on polyvinylpyrrolidone hydrogels. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: Polyvinylpyrrolidone (PVP) hydrogels have been investigated as drug delivery matrices for the treatment of wounds, such as cutaneous leishmaniasis, and matrices with silver nanoparticles for chronic wounds and burns. The preparation of such hydrogels can occur by various cross-linking methods, such as gamma, chemical, physical, among others. The most feasible for wound dressings is gamma irradiation from cobalt-60, because gamma irradiation simultaneously promotes crosslinking and sterilization, leaving the wound dressing ready for use. The objective of this work was to investigate the effect on physico- chemical properties of gamma radiation on PVP hydrogel according to the radiation absorbed dose variation. The PVP hydrogels were irradiated with doses of 5, 15, 25, 35, 45, 55, 65, 75 and 95kGy at dose rate of 5 kGy/h and characterized by swelling, thermogravimetric and mechanical analysis. Results shown a favorable dose range window for processing of these hydrogels related to the application. The results showed that mechanical strength was affected at doses starting at 25 kGy.

    Palavras-Chave: absorbed radiation doses; chemical properties; cobalt 60; differential thermal analysis; dose rates; fourier transformation; gamma radiation; hydrogels; infrared spectra; physical properties; pvp; radiation effects; swelling; tensile properties; thermal gravimetric analysis; wounds

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  • IPEN-DOC 26298

    LIMA, LENI M.P.R.; KODAMA, YASKO ; OTUBO, LARISSA ; SANTOS, PAULO de S. ; VASQUEZ, PABLO A. . Effect of ionizing radiation on the color of botanical collections: exsiccata. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2650-2661.

    Abstract: Conservation and preservation strategies are essential to manage botanical collections specially for dried herbarium specimens also known as exsiccates, usually referring to a set of identified specimens belonging to taxa and distributed among all herbaria around the world. Particularly, these collections are very sensitive to the attack of fungi and insects. In recent years, disinfection by ionizing radiation has become an effective strategy to preserve cultural heritage objects and archived materials with excellent results. In this work, the effects on color properties of gamma radiation on exsiccates samples were studied. Thus, six exsiccates, botanical pressed and dehydrated samples were selected from the Dom Bento José Pickel Herbarium (SPSF), situated at São Paulo (Brazil). Three of these samples comes from Asteraceae family and were collected in 1946, 1984 and 1986, while three other samples belong to Solanaceae family and were collected in 1953, 1984 and 2007. Families of selected botanical collections are very susceptible to biodegradation. The irradiation was performed at the Multipurpose Gamma Irradiation Facility at IPEN applying absorbed doses of 1 kGy, 6 kGy and 10 kGy, which are values of absorbed dose for disinfestation and disinfection. Results were analyzed using colorimetry with CIELAB color space scale and scanning electron microscopy. The results showed that there were no significant changes on colorimetric morphological properties of the samples.

    Palavras-Chave: absorbed radiation doses; botany; calorimetry; cobalt 60; disinfestation; fungi; gamma radiation; morphological changes; pest control; plants; radiation dose units; scanning electron microscopy

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  • IPEN-DOC 24186

    CARDOSO, JESSICA R. ; MOURA, EDUARDO de ; GERALDO, AUREA B.C. . Electron beam irradiation process applied to primary and secondary recycled high density polyethylene. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: Plastic bags, packaging and furniture items are examples of plastic utilities always present in life. However, the end-of-life of plastics impacts the environment because of this ubiquity and also often their high degradation time. Recycling processes are important in this scenario because they offer many solutions to this problem. Basically, four ways are known for plastic recycling: primary recycling, which consists in re-extrusion of clean plastic scraps from a production plant; secondary recycling, that uses end-of-life products that generally are reduced in size by extrusion to obtain a more desirable shape for reprocessing (pellets and powder); tertiary recover which is related to thermo-chemical methods to produce fuels and petrochemical feedstock; and quaternary route, that is related to energy recovery and it is done in appropriate reactors. In this work, high density polyethylene (HDPE) was recovered to simulate empirically the primary and secondary recycling ways using materials which ranged from pristine to 20-fold re-extrused materials. The final 20-fold recycled thermoplastic was irradiated in an electron beam accelerator under a dose rate of 22.4 kGy/s and absorbed doses of 50 kGy and 100 kGy. The characterization of HDPE in distinct levels of recovering was performed by infrared spectroscopy (FTIR) and thermogravimetric degradation. In the HDPE recycling, degradation and crosslinking are consecutive processes; degradation is very noticeable in the 20-fold recycled product. Despite this, the 20-fold recycled product presents crosslinking after irradiation process and the post-irradiation product presents similarities in spectroscopic and thermal degradation characteristics of pristine, irradiated HDPE. These results are discussed.

    Palavras-Chave: absorbed radiation doses; cross-linking; dose rates; electron beams; extrusion; fourier transformation; infrared spectra; polypropylene; recycling; shear; thermal degradation

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  • IPEN-DOC 24107

    FUKUMORI, NEUZA T.O. ; MENGATTI, JAIR ; MATSUDA, MARGARETH M.N. . Evaluation of 99Mo/99mTc generator columns after irradiation with different absorbed doses. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: The 99Mo/99mTc generator is widely used in nuclear medicine and it consists of a glass column containing Teflon® strips and alumina in which 99Mo produced by 235U fission is adsorbed. The 99mTcO4- eluate shall meet the sterile and pyrogen free conditions for injectable radiopharmaceuticals as determined by the Good Manufacturing Practices. The purpose of this study was to evaluate the feasibility of using gamma radiation in the sterilization of the 99Mo/99mTc generator column and the influence on the elution efficiency. Alumina-containing columns were irradiated with 10, 15, 25 and 50 kGy absorbed doses. Alumina samples and control (non-irradiated) were submitted to X-ray diffraction and the combined use of scanning electron microscopy and elemental analysis. Teflon® samples were evaluated by thermogravimetry (TGA) and differential scanning calorimetry (DSC). X-ray diffractograms and micrographies with elemental analysis showed no significant changes in the crystalline structure of the alumina because it was stable α-Al2O3. TGA demonstrated that higher doses showed changes in lower temperatures and times than the control material. For DSC the higher the absorbed dose, the greater the polymer chain breakage and crosslinking in the material. The generator system without radioactivity was set up with the irradiated columns and the eluates demonstrated to be sterile and pyrogen free. The effects of different absorbed doses on the generator column, although some reported changes in the materials, demonstrated that the sterilization of the columns by irradiation with gamma rays as an alternative to wet heat sterilization is feasible from a technical and financial point of view.

    Palavras-Chave: absorbed radiation doses; aluminium oxides; calorimetry; cobalt 60; feasibility studies; molybdenum 99; radioisotope generators; sterilization; technetium 99; thermal gravimetric analysis

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  • IPEN-DOC 26290

    VIRGINIO, SUELI ; GERALDO, AUREA B.C. ; MACHADO, LUCI D.B. ; COSENTINO, IVANA C. ; MATOS, JIVALDO do R.. Evaluation of ordered mesoporous silica SBA-15 dispersed in epoxy resin. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2545-2551.

    Abstract: To obtain the mesoporous nanostructured SBA-15 silica particles, a chemical reaction was perfomed using a template – a triblock copolymer (Pluronic 123®) - and a silica source - the tetraethyl orthosilicate - in acid medium. These silica particles were obtained by classical chemical reaction method and irradiation process (gamma rays from 60Co-Gammacell) at absorbed dose values of 0.5 kGy, 10 kGy and 25 kGy. Then, these silica particles were dispersed in epoxy resin Araldite® GY260 (diglycidyl ether of bisphenol A - DGEBA) and a cure agent. The particles dispersion was evaluated by two methodologies: a) Melt blending mode, where silica particles are dispersed in hot resin; b) Solvent-blended solution mode, where silica particles are dispersed in epoxy resin/acetone mixture in order to prevent the agglomeration of the inorganic phase. The silica particles had the specific surface area calculated from BET (Brunauer-Emmett-Teller) equation, while the BJH (Barrett- Joyner-Halenda) equation was used to determine pore volume and average diameter. Silica particles presented high surface area and pores arranged in hexagonal nanoscale diameter. The TEM images for irradiated silica particles have confirmed the hexagonal pore ordering in SBA-15 even using low gamma absorbed doses. The infrared absorption spectra (FTIR) confirmed that the added organic solvent has been effectively removed. Images of optical microscope revealed dispersion of the components by solvent-blended solution mode allows a better components interaction.

    Palavras-Chave: absorbed radiation doses; cobalt 60; epoxides; fourier transformation; gamma radiation; infrared spectra; nanostructures; resins; silica; surfactants; transmission electron microscopy

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  • IPEN-DOC 18540

    MARTINS, ELAINE W.; POTIENS, MARIA da P.A. . Evaluation of radiation dose in computed tomography standard beams using simulators. In: INTERNATIONAL CONGRESS OF THE INTERNATIONAL RADIATION PROTECTION ASSOCIATION, 13th, May 13-18, 2012, Glasgow, Scotland. Proceedings... 2012.

    Palavras-Chave: computerized tomography; pediatrics; phantoms; surface air; kerma; absorbed radiation doses; dosimetry

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  • IPEN-DOC 20608

    BELLEZZO, MURILLO ; NASCIMENTO, EDUARDO do ; YORIYAZ, HELIO . A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phanton. In: INTERNATIONAL SYMPOSIUM ON SOLID STATE DOSIMETRY , 14th, April 13-16, 2014, Cusco, Peru. Proceedings... 2014. p. 377-390.

    Palavras-Chave: absorbed radiation doses; c codes; computer calculations; dose rates; dosimetry; monte carlo method; p codes; parallel processing; phantoms; photon transport; radiotherapy

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  • IPEN-DOC 20794

    CAVALCANTE, FERNANDA ; PECEQUILO, BRIGITTE R.S. . Natural and anthropogenic radionuclides in Brazilian commercial dog food: preliminary results. In: INTERNATIONAL CONFERENCE ON RADIOECOLOGY AND ENVIRONMENTAL RADIOACTIVITY, 3rd, September 7-12, 2014, Barcelona, Espanha. Proceedings... 2014.

    Palavras-Chave: absorbed radiation doses; americium 241; brazil; cats; cesium 137; cobalt 60; concentration ratio; dogs; food; gross domestic product; gamma spectroscopy; indium 100; ingestion; iodine 131; nitrogen; polyethylenes; potassium 40; radioecological concentration; radionuclide kinetics; ge semiconductor detectors

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  • IPEN-DOC 24051

    OLIVEIRA, ALINE S.G.R. de ; DAMATTO, SANDRA R. . Natural radioactivity and estimated dose in brazilian tobacco products. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: Tobacco products contain significant concentrations of natural radionuclides from 238U and 232Th series. The consumption of these products increases the internal dose of radiation due to the inhalation of the natural radionuclides. Studies from literature emphasize that tobacco products have measurable concentrations of 210Po and 210Pb, and may contribute significantly to the increase of internal radiation dose and a large number of lung cancer in smokers. The objectives of this work were to determine the concentrations (Bq/kg) of the radionuclides 226Ra, 228Ra, 210Pb and 210Po and calculate the internal doses of radiation due to the consumption of these products. In the present work 71 samples were analyzed, consisting of cigars, unflavored and flavored cigarettes, straw cigarettes, cigars and roll smoke. The samples were purchased in Brazilian popular commercial establishments. The analytical techniques employed were the gross alpha and beta measurement after radiochemical separation for the radionuclides 226Ra, 228Ra, 210Pb and alpha spectrometry for 210Po. The internal radiation doses were calculated with the activity concentrations determined and using the ICRP Publication 119 dose coefficients. An annual consumption of 3,650 kg of tobacco products was considered. The inhalation rates of each radionuclide followed the rates of the current literature. The estimated mean annual dose varied from 76 to 263μSv/y for the tobacco product studied in this work.

    Palavras-Chave: absorbed radiation doses; activity levels; alpha decay; alpha spectroscopy; beta decay; concentration ratio; inhalation; natural radioactivity; thorium 232; tobacco products; uranium 238

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  • IPEN-DOC 24102

    FUNARI, ANA P. ; ANTEBI, URI; SANTOS, LUIZ A.; VIEIRA, DANIEL P. ; MIRANDA, JURANDIR T. de; ALVES, NELSON M.; FREITAS, ANDERSON Z. de ; MATHOR, MONICA B. . Optical and histological evaluation in human tendon tissue sterilized by ionizing radiation. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: Sterilization by irradiation is a technique that is used by tissue banks aiming to eliminate contamination of human allografts, being a safe method, free of residue and used as final sterilization. After the tissue procurement, these undergo a series of processing stages and then are packaged and preserved by freezing. Despite aseptic care of the material those may be subjected to sterilization in the final packing by ionizing radiation, raising the security level of sterility of the tissue. The aim of this study was to evaluate the effects of application of ionizing radiation, produced by 60Co source in human tendons preprocessed (A-alcohol + antibiotic; B- H2O2 + ultrasound) obtained through collaboration with tissue banks and preserved by freezing in -80° C, the radiation absorbed doses in processing were 12.5, 15 and 25 kGy, each one with their corresponding non-irradiated control, to examine possible structural or morphological alterations. The irradiated samples and their controls were analyzed by means of optical coherence tomography (OCT) and optical coherence tomography polarization sensitive (PS-OCT), and histological tests had been stained with hematoxylin-eosin (HE). According to the results the tissue processed with alcohol/antibiotic in conjunction with irradiation proved to be the most effective.

    Palavras-Chave: absorbed radiation doses; alcohols; animal tissues; antibiotics; cobalt 60; freezing; histological techniques; ionizing radiations; radiation effects; sterilization; tendons; tomography

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  • IPEN-DOC 24058

    ANTUNES, PAULA C.G. ; VIJANDE, JAVIER; GIMENEZ-ALVENTOSA, VICENT; YORIYAZ, HELIO ; BALLESTER, FACUNDO. Photon energy-fluence correction factor in low energy brachytherapy. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: The AAPM TG-43 brachytherapy dosimetry formalism has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. The purpose of this work is to study the influence of photon energy-fluence in different media and to evaluate a proposal for energy-fluence correction factors for the conversion between dose-to-tissue ( ) tis D and dose-to-water ( ) w D .State-of-the art Monte Carlo (MC) calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone) in two different codes, MCNP and PENELOPE, which in all cases include a realistic modeling of the 125I low-energy brachytherapy seed in order to benchmark the formalism proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences using the large-cavity theory. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seed is proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases.

    Palavras-Chave: absorbed radiation doses; animal tissues; brachytherapy; corrections; dosimetry; iodine 125; monte carlo method; p codes; photon emission; protons; radiation source implants; water

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  • IPEN-DOC 26286

    MUNHOZ, PEDRO M. ; SILVA, LEONARDO G. de A. e ; HARADA, JULIO ; NASCIMENTO, FERNANDO C. ; CALVO, WILSON A.P. . Poly (butylene adipate co-terephthalate)/poly (lactic acid) (PBAT/PLA) blend characterization processed by electron beam. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2510-2524.

    Abstract: The aim of this research was to check the changes in the mechanical and thermal properties of poly(butylene adipate co-terephthalate)/poly(lactic acid) (PBAT/PLA) polymeric blend, which commercial name is Ecovio®, after radiation processing in different absorbed doses. PBAT and PLA are biodegradable polymers and the Ecovio® polymeric blend consists of at least 80% of polymers from renewable resources. The irradiation was performed in a Radiation Dynamics Inc. electron beam accelerator, with 1.5 MeV of energy and electric current of 25 mA. Samples were prepared for micrograph, mechanical and thermal analyses. These samples were irradiated with absorbed doses of 5 kGy, 10 kGy, 15 kGy, 25 kGy and 50 kGy. The samples, after irradiation, were submitted to experiments of ultimate strength, tensile strength, ultimate elongation, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed a good interaction between the components of the polymeric blends and the radiation effect on polymeric blend promoted changes in PBAT and PLA polymers, increasing tenacity of these biopolymers and consequently facilitating yarn formation in processing. In conclusion, these irradiated blends could be used to make environmental friendly products.

    Palavras-Chave: absorbed radiation doses; accelerators; calorimetry; electron beams; irradiation; mechanical properties; mixing; polymers; radiation dose units; scanning electron microscopy; thermodynamic properties

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