For the future implementation of high speed communication,safety remains one of the main concerns. To ensurethe safety of new applications, specifically the new 5G antennas,it is crucial to know that they will not cause any harm to thehuman body. There are a few ways to test how safe a systemusing high frequency radiation is but the industry standard is byusing the Specific Absorption Rate (SAR). The SAR is directlycorrelated to the initial temperature rise in the volume exposedto radiation which is what the method used in this report is basedon. The temperature rise in a skin-like phantom due to 5 GHzexposure was recorded using an IR-camera, which in turn wasused to calculate the SAR. The purpose of this report was to testif this method is a valid way of obtaining the peak surface SAR.It was concluded that the method is valid but there are someuncertainties in regards to abstracting the method to far-fieldexposure for our considered frequency. The SAR value that isachieved in this report is 333.4 W/Kg which is high in relationto the SAR-limits in IEEE guidelines, although the set up is notsupposed to reflect a realistic use of the antenna. This is due tothe fact that the waveguide in the setup is close to measurementsample, and has a higher intensity than is to be expected fromreal world applications. The method may be applicable for farfieldexposure with a higher frequency as that would concentratethe measurable heat to the surface of the measurement sampleand would also carry more energy by default. / För all framtida implementering avhöghastighetskommunikation kommer säkerhetsgarantin varaen av de stora frågorna. För att fastställa säkerheten hos nyatillämpningar, specifikt 5G antenner, är det viktigt att vetaatt det är oskadligt för människor. Det finns olika metoderför att påvisa säkerheten i applikationer som använder sig avhögfrekvent strålning men industristandarden är att användaSAR (Specific Absorption Rate). SAR är direkt korrelerat medvärmeutvecklingen i volymen utsatt för strålning vilket är detfaktum denna rapport är baserad på. Temperaturökningeni en skinnliknande fantom från 5 GHz-strålning mättes meden IR-kamera. Detta användes för att räkna ut SAR-värdet.Poängen med rapporten var att testa om denna metod äracceptabel för att räkna ut högsta SAR-värdet i en punkt.Slutsatsen är att denna metod fungerar men det kan finnasproblem med att abstrahera metoden till fjärrfält för vårtilltänka frekvens. Det uppnådda SAR-värdet är 333.4 W/Kgvilket är högt jämfört med IEEE-standarden, detta är på grundav att uppställningen inte är tänkt att återspegla en realistisksituation. Antennen är för nära fantomen och intensiteten ärockså högre än vad som används i vanliga fall. Metoden kanmöjligtvis användas vid fjärrfältstrålning vid högre frekvenseri och med att detta leder till en värmeökning koncentrad vidytan. Dessutom har högre frekvenser högre energi vilket innebären större värmeökning. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

Vacuum assisted delivery (VAD) is a common procedure used in the final stage of labor in the situation of a difficult natural delivery. Since the only biomechanical studies concerning the clinical safe traction force were conducted during 70s using simplified models to mimic the fetal head, concerns remain regarding the side effects of this medical intervention when applying high levels of traction forces. For experimental evaluation of VAD, a tissue-mimicking accurate fetal head phantom, having the same skull and brain dimension as a newborn, as well as, proper mechanical and acoustic properties of materials, can be used as a useful resource in terms of establishing safe levels of traction forces. The goal of this project is to develop a realistic patient-specific fetal head phantom that will be used to investigate the relation between applied traction force and imposed brain deformation in VAD in an experimental setting. A realistic fetal head phantom was developed using geometry accurate segmented meshes of pediatric skull and brain from a CT fetal head dataset. The fetal skull was 3D printed while the segmented mesh of the brain was used to create a fetal brain mold. The fetal brain phantom was developed using a PVA and graphite solution (10% and 3% mass concentration), whereas the sutures and fontanels, the scalp and the cerebrospinal fluid were mimicked using silicone, surgical latex and water, respectively. All the tissue-mimicking materials used corresponded with the biomechanical properties of the fetal head tissues. After the construction of the fetal head phantom, grey-scale long- and short- axis ultrasound images as well as the fetal brain phantom elasticity map were obtained. Furthermore, using sonomicrometry crystals, the reference strain values during manual hand pressure and VAD experimental procedures were acquired. The results showed negative strain values (compression) reaching 15% in the manual pressure experimental procedure, and higher positive strain values (stretching) reaching over 40% in the VAD experimental procedure. However, due to experimental limitations only one measurement using clinically realistic levels for both vacuum pressure (65 kPa) and traction force (70 N) was achieved. The developed fetal head phantom has potential to provide trustful biomechanical evidence to guide safe vacuum assisted delivery as well as to provide useful resource in terms of defining the clinical effective force of the vacuum extractor (VE). / I slutskedet av svåra vaginala förlossningar är assistans med sugklocka vanligt förekommande. Eftersom de enda biomekaniska studierna om kliniskt säkra dragkrafter genomfördes under 70 -talet med hjälp av förenklade modeller för att efterlikna fostrets huvud, finns det fortfarande oro om vilka skador användandet av sugklocka kan leda till när höga dragkrafter används. För att kunna fastställa en säker nivå av dragkrafter skulle en modell av fosterhuvudet, med realistiska dimensioner samt liknande mekaniska och akustiska egenskaper som en nyfödd, kunna användas.  Målet med detta projekt är att utveckla en realistisk patientspecifik modell av fosterhuvudet och sedan använda den för att experimentellt undersöka sambandet mellan applicerad dragkraft och hjärndeformation.  En realistisk fosterhuvudsmodell utvecklades från segmenterade datortomografibilder på ett fosterhuvud. Skallbenet tillverkades med en 3D-skrivare medan hjärnans gjöts i PVA och grafit (10% och 3% masskoncentration) i en 3D-utskriven form. Suturerna och fontanellerna, skalpen och cerebrospinalvätskan efterliknades med silikon, kirurgisk latex respektive vatten. Alla vävnadsimiterande material som användes motsvarade de biomekaniska egenskaperna hos ett fosters huvud.  När modellen var färdigkonstruerad togs ultraljudsbilder i gråskala i både lång- och kortaxel. Även hjärnmodellens elasticitet mättes med ultraljudsbaserad skjuvvågselastografi. Sonomikrometri –kristaller användes för att samla in referensvärden på hjärndeformation vid manuellt handtryck och experimentell rekonstruktion av förlossning med sugklocka. Resultaten visade att negativ deformation (kompression) på 15% i experimentella rekonstruktionen av förlossning. På grund av experimentella begränsningar uppnåddes dock endast en mätning med kliniskt realistiska nivåer för både vakuumtryck (65 kPa) och dragkraft (70 N).  Den utvecklade fosterhuvudsmodellen har i vidare studier potential att tillhandahålla tillförlitliga biomekaniska bevis för att vägleda säker vakuumassisterad förlossning samt för att definiera kliniska effektiva krafter i en sugklocka.

Background: PET nuclides can have a considerable influence on the spatial resolution and image quality of PET/CT scans, which can influence diagnostics in oncology, for example. The individual impact of the positron energy of ¹⁸F, ⁶⁸Ga, and ⁶⁴Cu on spatial resolution and image quality was compared for PET/CT scans acquired using a clinical, digital scanner. - Methods: A Jaszczak phantom and a NEMA PET body phantom were filled with ¹⁸F-FDG, ⁶⁸Ga-HCl, or ⁶⁴Cu-HCl, and PET/CT scans were performed on a Siemens Biograph Vision. Acquired images were analyzed regarding spatial resolution and image quality (recovery coefficients (RC), coefficient of variation within the background, contrast recovery coefficient (CRC), contrast–noise ratio (CNR), and relative count error in the lung insert). Data were compared between scans with different nuclides.- Results: We found that image quality was comparable between ¹⁸F-FDG and ⁶⁴Cu-HCl PET/CT measurements featuring similar maximal endpoint energies of the positrons. In comparison, RC, CRC, and CNR were degraded in ⁶⁸Ga-HCl data despite similar count rates. In particular, the two smallest spheres of 10 mm and 13 mm diameter revealed lower RC, CRC, and CNR values. The spatial resolution was similar between ¹⁸F-FDG and ⁶⁴Cu-HCl but up to 18% and 23% worse compared with PET/CT images of the NEMA PET body phantom filled with ⁶⁸Ga-HCl. - Conclusions: The positron energy of the PET nuclide influences the spatial resolution and image quality of a digital PET/CT scan. The image quality and spatial resolution of ⁶⁸Ga-HCl PET/CT images were worse than those of ¹⁸F-FDG or ⁶⁴Cu-HCl despite similar count rates.

Cardiovascular diseases are the leading causes of death worldwide and improved diagnostic methods are needed for early intervention and to select the most suitable treatment for patients. Currently, carotid artery plaque vulnerability is typically determined by visually assessing ultrasound B-mode images, which is influenced by user-subjectivity. Since plaque vulnerability is correlated to the mechanical properties of the plaque, quantitative techniques are needed to estimate plaque stiffness as a surrogate for plaque vulnerability, which would reduce subjectivity during plaque assessment. The work in this thesis focused on three noninvasive ultrasound-based techniques to quantitatively assess plaque vulnerability and measure arterial stiffness. In Study I, a speckle tracking algorithm was validated in vitro to assess strain in common carotid artery (CCA) phantom plaques and thereafter applied in vivo to carotid atherosclerotic plaques where the strain results were compared to visual assessments by experienced physicians. In Study II, hard and soft CCA phantom plaques were characterized with shear wave elastography (SWE) by using phase and group velocity analysis while being hydrostatically pressurized followed by validating the results with mechanical tensile testing. In Study III, feasibility of assessing the stiffness of simulated plaques and the arterial wall with SWE was demonstrated in an ex vivo setup in small porcine aortas used as a human CCA model. In Study IV, SWE and pulse wave imaging (PWI) were compared when characterizing homogeneous CCA soft phantom plaques. The techniques developed in this thesis have demonstrated potential to characterize carotid artery plaques. The results show that the techniques have the ability to noninvasively evaluate the mechanical properties of carotid artery plaques, provide additional data when visually assessing B-mode images, and potentially provide improved diagnoses for patients suffering from cerebrovascular diseases. / <p>Doctoral thesis in medical technology and medical sciences</p><p>QC 20160921</p>

Benjamin Fondane est un penseur et un artiste du XXe siècle qui demeure encore relativement méconnu de la communauté universitaire. Pourtant, son œuvre poétique et ses essais révèlent une démarche atypique et une vision concrète de la dualité humaine et de la pratique de la pensée. « Le mal des fantômes », poème central de l’œuvre de Fondane, est une incarnation imagée du mal-être psychique de l’humain qui pressent que ses réflexes intellectuels, tels la raison et l’esprit de non-contradiction, créent une rupture avec son expérience intime du monde, brigue une portion du réel. L’étude de la figure du fantôme (qui est la figure de la hantise dans la tradition littéraire) ainsi que de l’économie discursive de la traversée maritime qui se déploient dans ce poème nous permet d’interroger les astuces rhétoriques que Fondane met en place afin de contrecarrer ce malaise. À travers l’expérience scripturale et la lecture, il est à la recherche d’une nouvelle disposition de l’activité réflexive qui serait davantage solidaire de l’existence humaine. C’est grâce au geste de l’écriture que sa pensée voyage, se meut, retrouve sa vivacité et, par là même, ses pouvoirs de mutation. Se pencher sur la mise en œuvre de la réflexion chez Benjamin Fondane permet de poser un regard sensible sur les propres rapports que nous entretenons avec notre activité intellectuelle, scripturale et notre pensée. / Benjamin Fondane is a thinker and an artist of the twentieth century who is still relatively unknown to the academic community. However, his poetry and essays reveal an unusual flow of language and a concrete vision of human duality and practice of thought. “Le mal des fantômes,” Fondane’s central poem, is a image-laden incarnation of the human’s mental uneasiness in creating a disjunction between his or her intellectual reflexes, such as reason and the spirit of non-contradiction, and an intimate experience of the world, a disjunction that necessarily limits the mind to a mere portion of a larger, integral reality. In studying the “fantôme” trope – that is, the haunting figures of the literary tradition – in conjunction with the poem's discursive economy of the sea voyage, we seek to unveil the rhetorical ploys that Fondane mobilizes to counteract this malaise. Through writing and reading experimentation, he seeks a new paradigm of thinking that follows more closely unfolding human existence. By virtue of writing itself, thought travels, moves along, and regains both its vitality and transformative power. Moreover, considering the workings of Fondane’s thought enables us to examine the ongoing relationship between our own intellectual activity, writing, and thought.

Student Number : 9710738R - MSc (Eng) dissertation - Faculty of Engineering and the Built Environment / This dissertation investigates the use of digital modeling methods for selected medical applications. The digital methods include the design of a cranial implant, auricular prosthesis and the duplication of an oral prosthesis. The digital process includes imaging, image processing, design and fabrication steps. Three types of imaging used are contact and non-contact measurement systems and CT scanning. The investigation uses a Phantom haptic device for digital design. The implants and prostheses are fabricated using a Thermojet printer and investment casting. Traditional and digital processes are compared using four case studies on selected criteria. The conclusions of the investigation are that a digital process can be used and is equal to or better than traditional methods in prosthesis and implant design.

Trabalhos anteriores sobre a síntese de imagens de difusão por ressonância magnética se limitaram a estudos sobre estruturas microscópicas, menores que as dimensões típicas de um voxel (e.g., [BF08] [BF13] [LFS + 10] e [BA94]). Isto decorre em parte devido às metodologias utilizadas, que têm como ponto em comum serem simulações de tipo Monte Carlo, nas quais os elementos mínimos da simulação são as partículas de água. Portanto o custo computacional destas simulações é proporcional ao número de partículas a simular, e isto limita os volumes que podem ser simulados a tamanhos microscópicos. Propomos uma metodologia alternativa, que utiliza a imagem T 2 de uma amostra para sintetizar imagens de difusão por ressonância magnética. Os elementos mínimos desta nova metodologia são os pontos da imagem T 2 , e portanto seu custo computacional é proporcional à resolução da imagem T 2 utilizada, o que permite a síntese a partir de amostras de qualquer tamanho físico. Estas sínteses são realizadas por meio da integração numérica da equação do artigo seminal de Stejskal e Tanner [ST65] que relaciona a atenuação do sinal de ressonância magnética devida à difusão com os parâmetros da sequência de pulsos PGSE. Usamos os parâmetros típicos dessa sequência (b, gamma, tau\', g 0, g, delta e Delta), que podem ser configurados explicitamente em máquinas de ressonância magnética, para calcular valores do coeficiente de difusão aparente D em direções arbitrárias. Desenvolvemos software, disponibilizado [Bor] por licença GPL [Fou07], para realizar estas simulações, e para especificar uma máscara de direções, útil para modelar a difusão de uma amostra. Estas ferramentas permitem o estudo sistemático das variações dos parâmetros na síntese de imagens de difusão por ressonância magnética. Apresentamos um estudo de um fantoma de capilares imersos em água, exemplificando como utilizar as ferramentas para investigar a influência destes parâmetros na difusão da água da amostra. / Previous work on the synthesis of diffusion-weighted magnetic resonance imaging are limited to microscopic structures, smaller than the typical dimensions of a single voxel (e.g., [BF08] [BF13] [LFS + 10] and [BA94]). This is consequence, in part, of the methodologies used, that have in common the adoption of Monte Carlo simulation strategies, in which the minimal elements of simulation are the water particles. Therefore the computational cost of these simulations is proportional to the number of particles to simulate, and this limits the volume to be simulated to microscopic sizes. We propose a novel methodology, that uses the T 2 image from a sample to synthesize diffusion-weighted magnetic resonance images. The mininal elements of this novel methodology are the points of the T 2 image, and therefore its computational cost is proportional to the resolution of the T 2 image to be used, which allows the synthesis from samples of any physical size. These syntheses are made through numerical integration of the equation from the seminal article by Stejskal and Tanner [ST65] that relates the attenuation of the magnetic resonance signal due to diffusion to the parameters of the PGSE pulse sequence. We use the typical parameters of this sequence (b, gamma, tau\', g 0, g, delta and Delta), that can be explicitly configured in magnetic resonance machines, to calculate apparent diffusion coefficients D in arbitrary directions. We developed software, available [Bor] through GPL license [Fou07], to run these simulations, and to specify a mask of directions useful to model diffusion. These tools allow the systematic study of parameter variation in the synthesis of diffusion-weighted magnetic resonance images. We present a case study of a phantom made of capillary tubes immersed in water, to exemplify the use of these tools and how to investigate the influence of parameter variation on diffusion in the sample.

Orientador: Diana Rodrigues Pina / Resumo: A Radiologia Intervencionista (RI) é a área da medicina que proporciona as maiores exposições ocupacionais. Os valores de dose aos quais os intervencionistas são expostos são difíceis de padronizar. Nesta pesquisa apresentamos uma avaliação completa das exposições ocupacionais e determinamos a eficiência de distintos métodos de dosimetria pessoal utilizados na RI. Essa pesquisa foi abordada em 2 etapas, conforme descrito a seguir: A primeira etapa se baseou em caracterizar as exposições ocupacionais em diferentes modalidades de procedimentos de RI vascular para duas categorias de profissionais e estimar o número de procedimentos anuais que cada profissional pode realizar sem exceder os limites de dose. Foi avaliada a exposição ocupacional, através de dosimetria termoluminescente, em diferentes partes do corpo (cristalino, tireoide, tórax, abdômen, pés e mãos) de duas categorias de intervencionistas (principais e assistentes) em três modalidades diferentes de procedimentos de RI vascular. As maiores doses equivalentes foram encontradas para as mão de ambos os profissionais, podendo chegar a aproximadamente 9 mSv em um único procedimento. Algumas regiões dos profissionais em alguns procedimentos podem receber, durante o ano, níveis de doses perigosamente perto dos limites anuais. Dosímetros posicionados no tórax podem subestimar as doses para outras regiões do corpo, especialmente abdômen, extremidades e cristalinos. Na segunda etapa foram avaliadas as eficiências de 6 diferent... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Interventional Radiology (IR) is the area of medicine that provides the largest occupational exposures. The dose values to which interventionists are exposed are difficult to standardize. In this research we present a complete evaluation of occupational exposures and determine the efficiency of different personal dosimetry methods used in IR. This research was performed in 2 stages, as described below: The first step was to characterize the occupational exposures in different modalities of vascular IR procedures for two categories of professionals. We also estimated the number of annual procedures that each professional can perform without exceeding the dose limits. Occupational exposures were evaluated in different body parts (crystalline, thyroid, thorax, abdomen, feet and hands) by two interventional categories (primary and assistants) in three different modalities of vascular IR procedures. The highest equivalent doses were found for the hands of both professionals, reaching approximately 9 mSv in a single procedure. Some regions of professionals in some procedures may receive dose levels during the year dangerously close to annual limits. Dosimeters positioned in the chest may underestimate the doses to other regions of the body, especially the abdomen, extremities and crystalline. The second stage, we evaluated the efficiencies of 6 different personal dosimetry methodologies used internationally to estimate the effective dose received by interventional professionals. An... (Complete abstract click electronic access below) / Mestre

Ce travail de thèse a pour but de développer et de caractériser de nouveaux systèmes d'assurance qualité en curiethérapie, à base de sondes dosimétriques en Nitrure de Gallium (GaN). L'étude comprend d'une part la caractérisation et la simulation du transducteur GaN et de la sonde dosimétrique, et d'autre part la mise en œuvre et les tests de 2 systèmes d'assurance qualité.Les propriétés de radioluminescence du transducteur GaN ont été étudiées afin d'optimiser le signal dosimétrique des sondes. La sonde dosimétrique encapsulant un petit volume de cristal GaN a ensuite été caractérisée en vue de son intégration dans des systèmes d'assurance qualité. Des simulations Monte Carlo sur la sonde GaN ont également été effectuées et comparées aux mesures.Pour l'assurance qualité en curiethérapie, nous avons proposé une méthode utilisant plusieurs sondes GaN, pour permettre de déterminer en temps réel les principaux paramètres physiques d'un projecteur de source : la position, le temps de pause et l'activité de la source. Nous avons conçu et réalisé deux prototypes de systèmes d'assurance qualité mettant en œuvre cette méthode : un fantôme instrumenté pour le contrôle prétraitement et un applicateur gynécologique instrumenté pour le contrôle pendant le traitement. Ces deux prototypes ont été testés en conditions cliniques, et leurs principales caractéristiques sont satisfaisantes. Ils répondent aux besoins applicatifs et offrent une perspective intéressante pour de nouveaux outils de contrôle qualité en curiethérapie / This work aims to develop and characterize novel quality assurance systems based on Gallium Nitride (GaN) dosimeter probe for brachytherapy. It includes characterization and simulation studies of the GaN transducer and of the dosimeter probe as well as the implementation and testing of two quality assurance system prototypes.The radioluminescence properties of the GaN transducer have been studied for optimization of the dosimeter response. Characterization studies of dosimeter probes incorporating miniaturized GaN transducers have been carried out in the frame of the quality assurance systems development. Monte Carlo simulations of the GaN probe under irradiation has also been performed and compared with measurements.A method which processes simultaneously the output signals from several GaN probes has been proposed for real time determination of the projector’s physical parameters (dwell position, dwell time and activity of the source). Two quality assurance system prototypes implementing this method have been designed and fabricated: an instrumented phantom for pre-treatment quality assurance and an instrumented gynecological applicator for in vivo quality control. These two prototypes have been tested and evaluated in clinical conditions and their main characteristics are satisfactory. Both systems are in line with the application requirements and offers new perspectives for quality assurance in brachytherapy

This research project, Return of the Polynesian Phantom, investigates self-portraiture through the mediums of moving image, digital modeling, object making, and installation. It seeks to consider in these media an ambiguous threshold between lightness and darkness, the real and the fabricated. The proposition that it explores is that it is at such ambiguous thresholds that notions of identity are negotiated, and where the perception and interpretation of symbolic meaning renders identity phantom.