Made available in DSpace on 2014-10-09T12:43:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:44Z (GMT). No. of bitstreams: 1 06775.pdf: 15025996 bytes, checksum: fbd53da186ea56301e555ed353c39360 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-11-12T10:44:49Z No. of bitstreams: 0 / Made available in DSpace on 2015-11-12T10:44:49Z (GMT). No. of bitstreams: 0 / Um programa de monitoramento para fins de proteção radiológica deve mostrar como ele auxilia na obtenção e demonstração de um grau de proteção adequado e comprovar que as condições de trabalho continuam satisfatórias com o transcorrer do tempo. Para o controle operacional das exposições à radiação ionizante em qualquer local de trabalho, a Comissão Internacional de Proteção Radiológica (CIPR) recomenda um programa de proteção radiológica operacional, proporcional ao grau de risco, para garantir o gerenciamento efetivo das medidas necessárias para se satisfazer o principio da otimização. O presente trabalho de pesquisa tem como premissa o potencial das Tecnologias da Informação e Comunicação (TIC) como ferramenta para a comunicação e disseminação do conhecimento em Proteção Radiológica. O trabalho inclui a informatização da filosofia e técnica do monitoramento e sua otimização, unificando e inter-relacionando informações advindas de diversas publicações nacionais e internacionais, oferecendo às instalações radiativas brasileiras um veículo completo para informação e pesquisa, que permite dimensionar os esforços de otimização tornando-os eficazes e justificados. O sistema oferece ainda tópicos de discussões no intuito de ampliar o repertório dos profissionais do campo da proteção radiológica, suscitando novas reflexões a favor da segurança. Trata-se dos temas desenvolvidos nesta tese, a saber: a necessidade de um monitoramento auditor e discussões mais aprofundadas sobre as exposições potenciais. As reflexões propostas na presente tese vêm ao encontro das novas exigências internacionais, propondo ações passíveis de serem incorporadas na prática laboral. Dentro dos princípios da proteção radiológica, a implementação de um programa de monitoramento auditor permite avaliar se os critérios e ações previamente estabelecidas pelo Serviço de Proteção Radiológica são ou não atendidos, se foram implementados com eficácia e se permanecem adequados. Os fatos resultantes dos procedimentos de auditoria auxiliam a detectar deficiências no processo, possibilitando conclusões e recomendações diante de possíveis fatores desencadeadores de exposições indevidas. Por meio de exames sistemáticos das atividades realizadas em cada tipo de monitoramento, a auditoria infere segurança ao processo, respaldando o trabalhador na realização do monitoramento relacionado com a tarefa e respaldando a instalação, que empreende ações responsáveis a favor da segurança. Em relação às exposições potenciais, somente duas publicações da CIPR são expressivas e desenvolvem o assunto. Entretanto, ainda que forneçam a fundamentação teórica, são incompletas em seus exemplos. Há uma grande falta de conhecimento das probabilidades de falhas, o que atualmente constitui um vasto campo de pesquisa da proteção radiológica. A presente tese propõe, a partir de árvores de falhas, caminhos que auxiliam a quantificar probabilisticamente a ocorrência das exposições potenciais e a probabilidade de se atingir um determinado valor da dose. Acreditamos que o potencial das TIC contribuirá largamente para a disseminação da informação para as instalações radiativas, estimulando o desenvolvimento neste país de grandes extensões territoriais, onde permanece um desafio oferecer o acesso à informação ao maior número de pessoas possível, minimizando custos e maximizando resultados. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

RESUMO O objetivo deste estudo foi obter as densidades radiográficas de diferentes filmes periapicais por meio de um programa computadorizado que utiliza a imagem equivalente em alumínio (alumínio-equivalente). Avaliaram-se os filmes Agfa Dentus M2 “Comfort”, Kodak InSight, Kodak Ektaspeed Plus, Kodak Ultra-speed e Kodak D. Todos foram expostos aos raios X juntamente com um escalímetro de Alumínio, variando-se o tempo de exposição (0,1 a 1 segundo). Após a leitura das densidades radiográficas construiu-se um gráfico para compararmos as propriedades sensitométricas dos filmes. O filmes mais sensíveis foram o Agfa Dentus M2 “Comfort” e o Kodak InSight, e os menos sensíveis o Kodak Ultra-speed e o Kodak D. Os filmes Agfa Dentus M2 “Comfort” e Kodak InSight apresentaram os maiores contrastes. Os resultados obtidos por este método indicam que deve-se utilizar os filmes Agfa Dentus M2 “Comfort” e Kodak InSight para reduzir a dose de radiação recebida pelo paciente. / ABSTRACT The aim of this study was to obtain radiographic densities from different dental intraoral x-ray films through a software using aluminium-equivalent image. The densities had been measured in order to compare dental x-ray films in terms of speed, base plus fog, and contrast. Agfa Dentus M2 “Comfort”, Kodak InSight, Kodak Ektaspeed Plus, Kodak Ultra-speed and Kodak D-speed films were evaluated. All films were exposed together with aluminium wedge, at times ranging from 0,1-1 second. By plotting a graphic of density against exposure, sensitometric properties were compared. Agfa Dentus M2 “Comfort” and Kodak InSight films obtained the highest film speed; Kodak Ultra-speed and Kodak D-speed films exhibited the lowest sensitivity. Agfa Dentus M2 “Comfort” and Kodak InSight films had presented valuesm to contrast superior to other films. Therefore, Agfa Dentus M2 “Comfort” and Kodak InSight films must be recommended to minimize the radiation dose to the patient.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-03-06T13:16:04Z No. of bitstreams: 2 Dissertação - Lilian Soares Couto - 2017.pdf: 4439690 bytes, checksum: 714aa1514cdb6d691695bec489132c48 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-03-06T14:55:49Z (GMT) No. of bitstreams: 2 Dissertação - Lilian Soares Couto - 2017.pdf: 4439690 bytes, checksum: 714aa1514cdb6d691695bec489132c48 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-06T14:55:49Z (GMT). No. of bitstreams: 2 Dissertação - Lilian Soares Couto - 2017.pdf: 4439690 bytes, checksum: 714aa1514cdb6d691695bec489132c48 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-23 / The main test for early detection of breast cancer is mammography. In the last decade, there was a significant increase in the number of women undergoing mammography for screening of breast cancer and have breast implants. Despite the mammographic screening recommended for patients with implants, follow the same range as recommended for patients doesn’t have implants, routinely includes images with posterior displacement of the implant (ID), known as Eklund’s maneuver, adding four views in relation to who do not have it. This study aimed to evaluate the mammographic characteristics of the required views and the dose that these patients have received in the examination. Data collection was divided into two stages: the first, for radiological evaluation of images and the second for data collection of radiographic techniques for image production. The radiological evaluation was performed by radiologists, with experience in mammography reading, who independently answered a questionnaire about: 1) implant position, 2) overall improvement image, 3) amount of breast tissue seen in the maneuver in relation to the standard images, 4) if there were findings in the exams, e) which view these findings were seen. For the data of the mammographic techniques, from the records in the DICOM (Digital Imaging and Communications in Medicine) heading of each image were collected: voltage (kV) and current x time (mAs) emitted by the device, target/filter combination, breast thickness and mean glandular dose (DGM). The data were analyzed by means of statistical treatment. Regarding the radiological evaluation, the evaluators agreed that the amount of breast tissue in the in the ID views depends on the position of the implant and is smaller in the retroglandular position. There was a significant increase in the quality of the images with the displacement of the implant and there were no findings seen in the exams, which were not seen in those views. Regarding the radiation doses received by patients with implants, during the mammographic examination, the DGM exceeds the limit recommended by the agencies responsible for the protocols. This study suggests the need for continuity of the research, with an increase in the sample and optimization of the mammographic technique, in order to evaluate the risk benefit ratio of maintaining all views of augmentation mammograms. / O principal exame para detecção precoce do câncer de mama é a mamografia. Na última década, houve um crescimento expressivo do número de mulheres que realizam mamografia para o rastreamento do câncer de mama e possuem implantes mamários. Apesar do rastreamento mamográfico recomendado para as pacientes com implantes, seguir o mesmo intervalo que o preconizado para as pacientes que não possuem, inclui de rotina, imagens com deslocamento posterior do implante, conhecida como manobra de Eklund, adicionando-se quatro incidências em relação às que não possuem. Este trabalho propôs-se à avaliação das características mamográficas das incidências exigidas e da dose de radiação que estas pacientes têm recebido no exame. A coleta de dados foi dividida em duas etapas: a primeira, para avaliação radiológica das imagens e a segunda para levantamento dos dados das técnicas radiográficas para produção das imagens. A avaliação radiológica foi realizada por médicos radiologistas, com experiência em leitura de mamografias, que responderam de forma independente um questionário sobre: 1) posição do implante, 2) melhoria global em detalhe de imagem, 3) quantidade de tecido mamário visto na manobra de Eklund em relação as imagens padrões, 4) se houve alteração nos exames, e) em quais incidências estas alterações foram vistas. Para os dados das técnicas mamográficas, foram coletados, a partir dos registros no cabeçalho DICOM (Digital Imaging and Communications in Medicine) de cada imagem: tensão (kV) e corrente x tempo (mAs), combinação alvo/filtro, espessura da mama e dose glandular média (DGM). Os dados foram analisados por meio de tratamento estatístico. Em relação à avaliação radiológica, os avaliadores concordaram que a quantidade de tecido mamário nas imagens com deslocamento do implante, depende da posição em que o implante se encontra, sendo menor na posição retroglandular. Houve significativo aumento da qualidade das imagens com o deslocamento do implante e não houve nenhuma alteração vista nos exames, que não tenham sido visibilizadas nas imagens com a manobra. Quanto às doses de radiação recebidas pelas pacientes com implantes, durante o exame mamográfico, a DGM excede o limite preconizado pelas agências responsáveis pelos protocolos. Este estudo sugere a necessidade de continuidade da pesquisa, com incremento da amostra e otimização da técnica mamográfica, para que se possa avaliar, a relação benefício risco de se manter todas as incidências em mamografias de mulheres com implantes mamários.

No description available.

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Inom nuklearmedicin exponeras personal dagligen för joniserande strålning. Det kan vara både i form av en öppen strålkälla vid uppdrag av radiofarmaka och vid bildtagning där personalen hjälper och ger stöd till patienten som blivit injicerad. Vid uppdrag av radiofarmaka används strålskydd i form av sprutskydd och distansverktyg medan blyförkläde används vid kontakt med patienter. Dessa skydd är till för att minska skador som kan uppstå vid exponering. Den svenska strålsäkerhetsmyndigheten (SSM) har föreskrivit dosgränser som inte får överskridas för att minska risken för skador. Teknetium-99m (99mTc) är den vanligaste radionukliden inom den nuklearmedicinska verksamheten. Syftet med denna studie var att kartlägga strålningsexponeringen för personal som jobbar med 99mTc och på så sätt visa behovet av olika typer av strålskydd för att reducera stråldosen. I denna studie utfördes fingerdosmätningar vid uppdrag av 99mTc med hjälp av termoluminiscenta dosimetrar som placerades på de tre mest utsatta fingrarna, digitus I-III, bilateralt. Mätningarna genomfördes vid uppdrag utan strålskydd, med en pincett och med fullt strålskydd (sprutskydd samt två pincetter). Studien innefattar även stråldosmätningar med och utan blyförkläde för myokardscintigrafi, skelettscintigrafi och lungscintigrafi. Dessa mätningar utfördes med en direktavläsande personal electronic dosimeter (PED) där den effektiva dosen registrerades. Resultaten för fingerdosmätningarna visar en signifikant skillnad i stråldos beroende på om och vilket strålskydd som används. Högst dos fick de som drog upp helt utan strålskydd och vänster långfinger fick den högsta ekvivalenta dosen. För stråldosmätningarna med och utan blyförkläde utfördes ett Mann-Whitney U-test som visade ett p-värde på <0,05 vilket tyder på att det finns en statistisk signifikant skillnad. Högst effektiv dos uppmättes vid lungscintigrafi för personal som inte använde blyförkläde. / Personnel working with radiopharmaceuticals in the nuclear medicine department are exposed to radiation on the daily basis. The source of radiation can both be open as in the withdrawal procedure and external as when the patient has been injected and ready for imaging. There are different types of radiation protection depending on which task that is performed. Syringe shielding and distance tools are used during the withdrawal and lead aprons are used when positioning the patient under the camera. The Swedish radiation safety authority (SSM) prescribe dose limits to reduce any risk of injury connected to radiation. These limits must not be exceeded. Technetium-99m (99mTc) is the most common radiopharmaceutical in the nuclear medicine department. The purpose of this study was to study the radiation exposure to personnel working with 99mTc and evaluate the need for radiation protection to reduce the radiation dose. This study includes measurement of the equivalent dose to the three most exposed fingers, digitus I-III bilateral, during the withdrawal of 99mTc. Thermoluminiscent dosimeters was used to detect radiation and was placed on top of the finger. The measurements were performed without radiation shielding, with only one tweezer as distance tool and with full radiation shielding (syringe shielding and two tweezers as distance tools). It also includes measurement of the effective dose during myocardial scintigraphy, bone scan and lung scintigraphy with or without lead apron. For these measurements a personal electronic dosimeter was used to detect radiation. The result of the finger doses showed a significant difference in radiation dose depending on which protection was used. The highest dose was recovered from not using any protection at all and the highest equivalent dose was obtained by left middle finger. For the measurement regarding the effective dose with or without lead apron a Mann-Whitney U-test was performed and showed a p-value of <0,05 which indicates a statistical significant difference. The highest effective dose was recovered from lung scintigraphy when the personnel was not wearing a lead apron.

Beam dumps are installed at the experimental areas of the ELBE facility. Their purpose is to absorb the primary electron beam and the secondary radiation. The beam dump consists of a purified graphite core inside a water cooled stainless steel vessel. The radiation shield surrounding the beam dump will be designed individually for each experimental area. In this context, dose rate calculations were carried out to estimate the dose rate source term around the stainless steel vessel of the beam dump. Detailed Monte Carlo simulations were carried out using the code FLUKA. The energy dependent photon and neutron fluences and the equivalent dose rates were obtained near the surface of the cylindrical steel vessel for a beam current of 1 mA and energies of 20 MeV and 50 MeV.

Synchrocyclotrons and laser based particle accelerators, developed with the goal to enable more compact particle therapy facilities, may bring highly pulsed radiation field to external beam radiation therapy. In addition, such highly pulsed fields may be desirable due to their potential clinical benefits regarding better healthy tissue sparing or improved gating for moving tumors. However, they pose new challenges for dosimetry, the corner stone of any application of ionizing radiation. These challenges affect both clinical and radiation protection dosimetry. Air-filled ionization chambers, which dominate clinical dosimetry, face the problem of increased signal loss due to volume recombination when a highly pulsed field liberates a large amount of charge in a short time in the chamber. While well established descriptions exist for this volume recombination for the moderately pulsed fields in current use (Boag's formulas), the assumptions on which those descriptions are based will most likely not hold in the prospective, highly pulsed fields of future accelerators. Furthermore, ambient dose rate meters used in radiation protection dosimetry as survey meters or fixed installations are generally only tested for continuous fields, casting doubt on their suitability to measure pulsed fields. This thesis investigated both these aspects of dosimetry - clinical as well as radiation protection - to enable the medical application of highly pulsed radiation fields. For a comprehensive understanding, experimental investigations were coupled with theoretical considerations and developments. Pulsed fields, varying in both dose-per-pulse and pulse duration over a wide range, were generated with the ELBE research accelerator, providing a 20 MeV pulsed electron beam. Ionization chambers for clinical dosimetry were investigated using this electron beam directly, with an aluminium Faraday cup providing the reference measurement. Whereas the dose rate meters were irradiated in the photon field generated from stopping the electron beam in the Faraday cup. In those measurements, the reference was calculated from the ionization chamber, then serving a an electron beam monitor, cross-calibrated to the photon field with thermoluminescent dosimeters. Three dose rate meters based on different operating principles were investigated, covering a large portion of the operating principles used in radiation protection: the ionization chamber based RamION, the proportional counter LB 1236-H10 and the scintillation detector AD-b. Regarding clinical dosimetry, measurements of two prominent ionization chamber geometries, plane-parallel (Advanced Markus chamber) and thimble type (PinPoint chamber), were performed. In addition to common air-filled chambers, chambers filled with pure nitrogen and two non-polar liquids, tetramethylsilane and isooctane, were investigated. In conjunction with the experiments, a numerical solution of the charge liberation, transport, and recombination processes in the ionization chamber was developed to calculate the volume recombination independent of the assumptions necessary to derive Boag's formulas. Most importantly, the influence of the liberated charges in the ionization chamber on the electric field, which is neglected in Boag's formulas, is included in the developed calculation. Out of the three investigated dose rate meters only the RamION could be identified as an instrument truly capable of measuring a pulsed field. The AD-b performed below expectations (principally, a scintillator is not limited in detecting pulsed radiation), which was attributed to the signal processing, emphasizing the problem of a typical black-box signal processing in commercial instruments. The LB 1236-H10, on the other hand, performed as expected of a counting detector. While this supports the recent effort to formalize these expectations and standardize testing for counting dosimeters in DIN IEC/TS 62743, it also highlights the insufficiency of counting detectors for highly pulsed fields in general and shows the need for additional normative work to establish requirements for dose rate meters not based on a counting signal (such as the RamION), for which no framework currently exists. With these results recognized by the German radiation protection commission (SSK) the first steps towards such a framework are taken. The investigation of the ionization chambers used in radiation therapy showed severe discrepancies between Boag's formulas and the experimentally observed volume recombination. Boag's formulas describe volume recombination truly correctly only in the two liquid-filled chambers. All the gas-filled chambers required the use of effective parameters, resulting in values for those parameters with little to no relation to their original meaning. Even this approach, however, failed in the case of the Advanced Markus chamber for collection voltages ≥ 300 V and beyond a dose-per-pulse of about 100 mGy. The developed numerical model enabled a much better calculation of volume recombination and allowed the identification of the root of the differences to Boag's formulas as the influence of the liberated charges on the electric field. Increased positive space charge due to increased dose-per-pulse slows the collection and reduces the fraction of fast, free electrons, which are unaffected by volume recombination. The resultant increase in the fraction of charge undergoing volume recombination, in addition to the increase in the total amount of charge, results in an increase in volume recombination with dose-per-pulse that is impossible to describe with Boag's formulas. It is particularly relevant in the case of high electric fields and small electrode distances, where the free electron fraction is large. In addition, the numerical calculation allows for arbitrary pulse durations, while Boag's formulas apply only to very short pulses. In general, the numerical calculation worked well for plane-parallel chambers, including those filled with the very diverse media of liquids, nitrogen and air. Despite its increased complexity, the thimble geometry could be implemented as well, although, in the case of the PinPoint chamber, some discrepancies to the experimental data remained, probably due to the required geometrical approximations. A possible future development of the numerical calculation would be an improved description of the voltage dependence of the volume recombination. At the moment it requires characterizing a chamber at each desired collection voltage, which could be eliminated by an improved modeling of the volume recombination's dependence on collection voltage. Nevertheless, the developed numerical calculation presents a marked improvement over Boag's formulas to describe the dose-per-pulse dependence and pulse duration dependence of volume recombination in ionization chambers, in principle enabling the application of ionization chambers in the absolute dosimetry of highly pulsed fields.

Der Einfluss der direkten Sonnenstrahlung kann trotz Strahlungsschutz und Ventilation zu deutlichen Fehlern bei der Bestimmung der Lufttemperatur führen. Zur Verringerung des Strahlungsfehlers in einer ventilierten Hütte wurde um die Temperatur- und Feuchtesensoren doppelte Strahlungsschutzrohre angebracht. Vergleichsexperimente haben gezeigt, dass damit ein wesentlich besserer Schutz vor der direkten Sonnenstrahlung erreicht wurde. / The influence of direct solar radiation and – despite a radiation shelter and sufficient ventilation – may cause an overestimation of the air temperature. To reduce the influence of the direct radiation, a double radiation protection tube was mounted around the temperature sensor. A cross validation has demonstrated, that consequently a much better radiation protection was realized.