Results of radiation protection programmes on mammography

In this paper, we present the results of mammography quality control tests related to the work with Portuguese mammography equipment, either in conventional or in digital mammography computed radiography, showing the main differences in the tested equipments. Quality control in mammography is a very special area of quality control in radiology, which demands relatively high knowledge on physics. Digital imaging is changing the standards of the radiographic imaging. Regarding mammography, this is yet a controversial issue owing to some limitations of the digital detectors, like the resolution for instance. A complete set of results regarding radiation protection of the patients submitted to mammography diagnosis is presented. A discussion of the quality image parameters and its interpretation in conventional and digital mammography is presented. In conclusion, we present a sample of results that can be considered as characteristics of mammography equipment in Portugal.

Comparison of different breast planning techniques and algorithms for radiation therapy treatment

This work aims at investigating the impact of treating breast cancer using different radiation therapy (RT) techniques ��� forwardly-planned intensity-modulated, f-IMRT, inversely-planned IMRT and dynamic conformal arc (DCART) RT ��� and their effects on the whole-breast irradiation and in the undesirable irradiation of the surrounding healthy tissues. Two algorithms of iPlan BrainLAB treatment planning system were compared: Pencil Beam Convolution (PBC) and commercial Monte Carlo (iMC). Seven left-sided breast patients submitted to breast-conserving surgery were enrolled in the study. For each patient, four RT techniques ��� f-IMRT, IMRT using 2-fields and 5-fields (IMRT2 and IMRT5, respectively) and DCART ��� were applied. The dose distributions in the planned target volume (PTV) and the dose to the organs at risk (OAR) were compared analyzing dose���volume histograms; further statistical analysis was performed using IBM SPSS v20 software. For PBC, all techniques provided adequate coverage of the PTV. However, statistically significant dose differences were observed between the techniques, in the PTV, OAR and also in the pattern of dose distribution spreading into normal tissues. IMRT5 and DCART spread low doses into greater volumes of normal tissue, right breast, right lung and heart than tangential techniques. However, IMRT5 plans improved distributions for the PTV, exhibiting better conformity and homogeneity in target and reduced high dose percentages in ipsilateral OAR. DCART did not present advantages over any of the techniques investigated. Differences were also found comparing the calculation algorithms: PBC estimated higher doses for the PTV, ipsilateral lung and heart than the iMC algorithm predicted.

Integra����o da tecnologia Near Field Communications nas telecomunica����es m��veis

O telem��vel tem-se transformado numa ferramenta essencial no nosso dia-a-dia, constantemente s��o lan��adas novas tecnologias que potenciam o uso do telem��vel nas tarefas do nosso quotidiano. Atualmente a grande tend��ncia passa por fazer o download de aplica����es com o objetivo de obter mais e diferentes tipos de informa����o, existe o desejo de ler de forma simples e intuitiva o mundo que nos rodeia, como se cada elemento fosse um objeto sobre o qual conseguiremos obter informa����o atrav��s do telem��vel. A tecnologia Near Field Communication (NFC) ajuda a transformar este desejo ou necessidade numa realidade de simples alcance. Podemos anexar ���identificadores��� nos objetos e ���ver��� estes identificadores atrav��s do telem��vel recorrendo a aplica����es que fazem a ponte com os sistemas que nos permitem obter mais informa����o, por exemplo, internet. O NFC especifica um padr��o de comunica����o de redes sem fios, que permite a transfer��ncia de dados entre dois dispositivos separados por uma dist��ncia m��xima de 10cm. NFC foi desenhado para ser integrado em telem��veis, que podem comunicar com outros telem��veis equipados com NFC ou ler informa����o de cart��es ou tags. A disserta����o avalia as oportunidades que a tecnologia NFC oferece ao mundo das telecomunica����es m��veis, nomeadamente na realidade do operador Vodafone Portugal, principalmente numa rela����o Empresa - Cliente. Esta tecnologia re��ne o interesse dos fabricantes dos telem��veis, dos operadores e de parceiros cr��ticos que v��o ajudar a potenciar o neg��cio, nomeadamente entidades banc��rias e interbanc��rias. A tecnologia NFC permite utilizar o telem��vel como um cart��o de cr��dito/debito, ticketing, ler informa����o de posters (Smart Poster) que despoletem navega����o contextualizada para outras aplica����es ou para a internet para obter mais informa����o ou concretizar compras, estes s��o alguns cen��rios identificados que mais valor o NFC consegue oferecer. A disserta����o foca-se na avalia����o t��cnica do NFC na ��rea de Smart Posters e resulta na identifica����o num conjunto de novos cen��rios de utiliza����o, que s��o especificados e complementados com o desenvolvimento de um prot��tipo.

Capillary bridging and long-range attractive forces in a mean-field approach

When a mixture is confined, one of the phases can condense out. This condensate, which is otherwise metastable in the bulk, is stabilized by the presence of surfaces. In a sphere-plane geometry, routinely used in atomic force microscope and surface force apparatus, it, can form a bridge connecting the surfaces. The pressure drop in the bridge gives rise to additional long-range attractive forces between them. By minimizing the free energy of a binary mixture we obtain the force-distance curves as well as the structural phase diagram of the configuration with the bridge. Numerical results predict a discontinuous transition between the states with and without the bridge and linear force-distance curves with hysteresis. We also show that similar phenomenon can be observed in a number of different systems, e.g., liquid crystals and polymer mixtures. (C). 2004 American Institute of Physics.

Radiatively induced Lorentz and CPT violation in Schwinger constant field approximation

The Schwinger proper-time method is an effective calculation method, explicitly gauge-invariant and nonperturbative. We make use of this method to investigate the radiatively induced Lorentz- and CPT-violating effects in quantum electrodynamics when an axial-vector interaction term is introduced in the fermionic sector. The induced Lorentz- and CPT-violating Chern-Simons term coincides with the one obtained using a covariant derivative expansion but differs from the result usually obtained in other regularization schemes. A possible ambiguity in the approach is also discussed. (C) 2001 Published by Elsevier Science B.V.

Increasing source to image distance for AP pelvis imaging: impact on radiation dose and image quality

Aim - A quantative primary study to determine whether increasing source to image distance (SID), with and without the use of automatic exposure control (AEC) for antero-posterior (AP) pelvis imaging, reduces dose whilst still producing an image of diagnostic quality. Methods - Using a computed radiography (CR) system, an anthropomorphic pelvic phantom was positioned for an AP examination using the table bucky. SID was initially set at 110 cm, with tube potential set at a constant 75 kVp, with two outer chambers selected and a fine focal spot of 0.6 mm. SID was then varied from 90 cm to 140 cm with two exposures made at each 5 cm interval, one using the AEC and another with a constant 16 mAs derived from the initial exposure. Effective dose (E) and entrance surface dose (ESD) were calculated for each acquisition. Seven experienced observers blindly graded image quality using a 5-point Likert scale and 2 Alternative Forced Choice software. Signal-to-Noise Ratio (SNR) was calculated for comparison. For each acquisition, femoral head diameter was also measured for magnification indication. Results - Results demonstrated that when increasing SID from 110 cm to 140 cm, both E and ESD reduced by 3.7% and 17.3% respectively when using AEC and 50.13% and 41.79% respectively, when the constant mAs was used. No significant statistical (T-test) difference (p = 0.967) between image quality was detected when increasing SID, with an intra-observer correlation of 0.77 (95% confidence level). SNR reduced slightly for both AEC (38%) and no AEC (36%) with increasing SID. Conclusion - For CR, increasing SID significantly reduces both E and ESD for AP pelvis imaging without adversely affecting image quality.

Guest editorial: OPTIMAX 2013

In 2012 we were awarded an Erasmus Intensive Programme grant to facilitate OPTIMAX 2013, a three week duration residential summer school held within the UK during August 2013. The summer school helped to further develop student radiographer skills in optimising x-radiation dose and image quality. With a major emphasis on visual techniques to determine image quality, lesion visibility, lesion detection performance and physical measures of image quality (eg signal to noise ratio (SNR)) we conducted controlled laboratory experiments on phantoms using Computed Radiography, CT and Full Field Digital Mammography. Mathematical modelling was used for radiation dose estimation. Sixty seven people from 5 European countries participated. This included 49 PhD, MSc and BSc students. Discipline areas included radiography, physics, biomedical science and nuclear medicine.

Contributo da radioterapia na melhoria dos cuidados de sa��de no Centro Nacional de Oncologia - Luanda

Mestrado em Radia����es Aplicadas ��s Tecnologias da Sa��de - ��rea de especializa����o: Terapia com Radia����es

Relat��rio de est��gio de natureza profissional em PET/CT: Clinical Imaging Sciences Centre, Sussex

Mestrado em Medicina Nuclear - Ramo de especializa����o: Tomografia por Emiss��o de Positr��es

Efeitos auditivos em doentes com tumores de cabe��a e pesco��o e tumores cerebrais sujeitos a Radioterapia e terapia combinada

Introdu����o: A capacidade auditiva dos doentes com neoplasias de cabe��a e pesco��o e tumores cerebrais pode ser comprometida com os tratamentos antineopl��sicos realizados. A Quimioterapia com cisplatina pode provocar perda auditiva de condu����o ou neurossensorial, podendo agravar-se quando combinada com Radioterapia (RT). O objectivo deste trabalho foi a an��lise da rela����o entre a Terapia Combinada (Cisplatina+RT) e a Radioterapia isolada, e os seus efeitos adversos sobre a audi����o tendo em considera����o a inclus��o das estruturas do ouvido no campo de tratamento de RT. M��todos: Foram seguidos 10 doentes submetidos a Terapia Combinada (grupo TC) e 11 a Radioterapia isolada (grupo RT). A avalia����o audiol��gica realizou-se antes do inicio (M1), no fim (M2) e um m��s ap��s (M3) o termo dos tratamentos e incluiu anamnese audiol��gica, otoscopia e audiometria tonal. Resultados: No grupo TC, 94,4% dos doentes apresentaram uma rela����o directamente proporcional entre a dose de radia����o na c��clea e a perda auditiva. Esta rela����o s�� se verificou em 31% dos doentes do grupo RT, tendo-se verificado diferen��as significativas entre grupos (p <0,001). Conclus��es: Verificou-se maior incid��ncia da perda auditiva no grupo TC relativamente ao grupo RT. Sugere-se um melhor planeamento do tratamento de RT, reduz - indo a dose �� c��clea com o objectivo de minimizar a perda auditiva neurossensorial irrevers��vel, sobretudo quando s��o utilizadas as duas modalidades de tratamento.

Planeamento de curto prazo de sistemas de energia solar usando t��cnicas de otimiza����o robusta

Disserta����o para obten����o do grau de Mestre em Engenharia Electrot��cnica

Gamma radiation effects on microbial inactivation of two medicinal plants

The consumption of natural products has become a public health problem, since these medicinal teas are prepared using natural plants without an effective hygienic and sanitary control. The aim of this study was to assess the effects of gamma radiation, on the microbial burden of two medicinal plants: Melissa officinalis and Lippia citriodora. Dried samples of the two plants were irradiated at a Co-60 experimental equipment. The applied gamma radiation doses were 1, 3, and 5 kGy at a dose rate of 1.34 kGy/h. Non-irradiated samples followed all the experiments. Bacterial and fungal counts were assessed before and after irradiation by membrane filtration method. Challenging tests with Escherichia coli were performed in order to evaluate the disinfection efficiency of gamma radiation treatment. Characterization of M. officinalis and L. citriadora microbiota indicated an average bioburden value of 102CFU/g. The inactivation studies of the bacterial mesophilic population of both dried plants pointed out to a one log reduction of microbial load after irradiation at 5 kGy. Regarding the fungal population, the initial load of 30 CFU/g was only reduced by 0.5 log by an irradiation dose of 5 kGy. The dynamics with radiation doses of plants microbial population���s phenotypes indicated the prevalence of gram-positive rods for M. officinalis before and after irradiation, and the increase of the frequency of gram-negative rods with irradiation for L. citriadora. Among fungal population of both plants, Mucor, Neoscytalidium, Aspergillus and Alternaria were the most isolated genera. The results obtained in the challenging tests with E. coli on plants pointed out to an inactivation efficiency of 99.5% and 99.9% to a dose of 2 kGy, for M.officinalis and L. citriadora, respectively. The gamma radiation treatment can be a significant tool for the microbial control in medicinal plants.