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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Creation and Evaluation of Solid Optical Tissue Phantoms for Bio-Medical Optics Applications

Hartleb, Carina January 2005 (has links)
<p>Because of their compatibility and precise results bio-optical methods based on measurements of the optical tissue properties gain importance in non-invasive medical therapy and diagnostic. For development and standardization of medical devices optical phantoms are suitable. The present report handles the creation and evaluation of solid tissue phantoms, made up of Agar, Vasolipid and ink utilizing different mixture ratios. After cutting the models in slices of 0.2 to 1.1 mm thickness the absorption- and scattering coefficient were measured using a collimated laser beam setup. As result of the study a formula for the preparation of solid optical tissue phantoms with desired optical properties was found, that is valid for models containing 1.12 % Agar.</p>
142

Development and Evaluation of an Inertial Sensor for Gait Analysis

Nutti, Björn January 2006 (has links)
<p>Hasomed GmbH, a German company in the Field of medicine technology, intends to introduce a gait analysis system on the market. The system includes an inertial sensor which collects data used for generating movement patterns of the feet. This thesis describes the development and evaluation of a new version of the sensor, aimed at minimizing costs, maximizing performance and facilitating production.</p><p>Algorithms used in the gait analysis system are sensitive to noise. Noise sources and precautions taken in order to minimize noise levels are described and discussed. By minimizing the physical size of analogue electronics blocks, static noise and occasional high frequency components were substantially reduced.</p><p>New features including internal temperature sensors, firmware update via serial interface, self-test functions and a wireless link were implemented. Additional improvements are e.g. lower power consumption and an extension of the interface from 2 to 256 (theoretical limit) attached devices. By reducing the number of included components and PCB (Printed Circuit Board) layers, together with use of components that do not require advanced soldering techniques, easier and cheaper production was obtained.</p><p>Research and development presented in this thesis resulted in a sensor with overall good performance and new features.</p>
143

Processing of the Phonocardiographic Signal : methods for the intelligent stethoscope

Ahlström, Christer January 2006 (has links)
<p>Phonocardiographic signals contain bioacoustic information reflecting the operation of the heart. Normally there are two heart sounds, and additional sounds indicate disease. If a third heart sound is present it could be a sign of heart failure whereas a murmur indicates defective valves or an orifice in the septal wall. The primary aim of this thesis is to use signal processing tools to improve the diagnostic value of this information. More specifically, three different methods have been developed:</p><p>• A nonlinear change detection method has been applied to automatically detect heart sounds. The first and the second heart sounds can be found using recurrence times of the first kind while the third heart sound can be found using recurrence times of the second kind. Most third heart sound occurrences were detected (98 %), but the amount of false extra detections was rather high (7 % of the heart cycles).</p><p>• Heart sounds obscure the interpretation of lung sounds. A new method based on nonlinear prediction has been developed to remove this undesired disturbance. High similarity was obtained when comparing actual lung sounds with lung sounds after removal of heart sounds.</p><p>• Analysis methods such as Shannon energy, wavelets and recurrence quantification analysis were used to extract information from the phonocardiographic signal. The most prominent features, determined by a feature selection method, were used to create a new feature set for heart murmur classification. The classification result was 86 % when separating patients with aortic stenosis, mitral insufficiency and physiological murmurs.</p><p>The derived methods give reasonable results, and they all provide a step forward in the quest for an intelligent stethoscope, a universal phonocardiography tool able to enhance auscultation by improving sound quality, emphasizing abnormal events in the heart cycle and distinguishing different heart murmurs.</p>
144

Internationalization of French firms within the medical technology industry

Griot, Clémence January 2010 (has links)
<p>French SMEs within the medical technology industry follow an internationalization pattern which cannot completely be explained by traditional internationalization models. Going abroad is not a strategy to overcome challenges inherent to the medical technology industry. Instead, it is the positive consequence of their merge with internationalized firms, or an opportunity offered by their network.</p>
145

Distansuppföljning av ICD-patienter : En hälsoekonomisk utvärdering

Sandås, Therese, Karlström, Micaela January 2009 (has links)
<p>Uppsatsens syfte är att undersöka vilka ekonomiska effekter införandet av distansuppföljning för ICD-patienter har ur ett samhällsperspektiv. Delsyftet är att identifiera ekonomiska argument och kvalitativa aspekter för och emot införandet av tjänsten distansuppföljning.</p><p>Författarna har kommit fram till ett antal slutsatser. Att införa distansuppföljning som uppföljningsmetod för ICD-patienter istället för konventionella återbesök på sjukhus innebär stora kostnadsbesparingar. Nettonuvärdet uppgår till drygt 268 miljoner kronor efter femton år. Vid tidsperiodens slut erhålls en kostnadsbesparing på cirka 35,6 procent. De ekonomiska fördelarna överstiger kostnaderna redan efter ett år, och hela investeringskostnaden återfås efter sju år. Kvalitativa argument som talar för distansuppföljning är tidsbesparingar, förenklad uppföljning, bättre övervakning och att patienterna upplever en större trygghet.</p>
146

New Doppler-Based Imaging Methods in Echocardiography with Applications in Blood/Tissue Segmentation

Hovda, Sigve January 2007 (has links)
Part 1: The bandwidth of the ultrasound Doppler signal is proposed as a classification function of blood and tissue signal in transthoracial echocardiography of the left ventricle. The new echocardiographic mode, Bandwidth Imaging, utilizes the difference in motion between tissue and blood. Specifically, Bandwidth Imaging is the absolute value of the normalized autocorrelation function with lag one. Bandwidth Imaging is therefore linearly dependent on the the square of the bandwidth estimated from the Doppler spectrum. A 2-tap Finite Impulse Response high-pass filter is used prior to autocorrelation calculation to account for the high level of DC clutter noise in the apical regions. Reasonable pulse strategies are discussed and several images of Bandwidth Imaging are included. An in vivo experiment is presented, where the apparent error rate of Bandwidth Imaging is compared with apparent error rate of Second-Harmonic Imaging on 15 healthy men. The apparent error rate is calculated from signal from all myocardial wall segments defined in \cite{Cer02}. The ground truth of the position of the myocardial wall segments is determined by manual tracing of endocardium in Second-Harmonic Imaging. A hypotheses test of Bandwidth Imaging having lower apparent error rate than Second-Harmonic Imaging is proved for a p-value of 0.94 in 3 segments of end diastole and 1 segment in end systole on non averaged data. When data is averaged by a structural element of 5 radial, 3 lateral and 4 temporal samples, the numbers of segments are increased to 9 in end diastole and to 6 in end systole. These segments are mostly located in apical and anterior wall regions. Further, a global measure GM is defined as the proportion of misclassified area in the regions close to endocardium in an image. The hypothesis test of Second-Harmonic Imaging having lower GM than Bandwidth Imaging is proved for a p-value of 0.94 in the four-chamber view in end systole in any type of averaging. On the other side, the hypothesis test of Bandwidth Imaging having lower GM than Second-Harmonic Imaging is proved for a p-value of 0.94 in long-axis view in end diastole in any type of averaging. Moreover, if images are averaged by the above structural element the test indicates that Bandwidth Imaging has a lower apparent error rate than Second-Harmonic Imaging in all views and times (end diastole or end systole), except in four-chamber view in end systole. This experiment indicates that Bandwidth Imaging can supply additional information for automatic border detection routines on endocardium. Part 2: Knowledge Based Imaging is suggested as a method to distinguish blood from tissue signal in transthoracial echocardiography. This method utilizes the maximum likelihood function to classify blood and tissue signal. Knowledge Based Imaging uses the same pulse strategy as Bandwidth Imaging, but is significantly more difficult to implement. Therefore, Knowledge Based Imaging and Bandwidth Imaging are compared with Fundamental Imaging by a computer simulation based on a parametric model of the signal. The rate apparent error rate is calculated in any reasonable tissue to blood signal ratio, tissue to white noise ratio and clutter to white noise ratio. Fundamental Imaging classifies well when tissue to blood signal ratio is high and tissue to white noise ratio is higher than clutter to white noise ratio. Knowledge Based Imaging classifies also well in this environment. In addition, Knowledge Based Imaging classifies well whenever blood to white noise ratio is above 30 dB. This is the case, even when clutter to white noise ratio is higher than tissue to white noise ratio and tissue to blood signal ratio is zero. Bandwidth Imaging performs similar to Knowledge Based Imaging, but blood to white noise ratio has to be 20 dB higher for a reasonable classification. Also the highpass filter coefficient prior to Bandwidth Imaging calculation is discussed by the simulations. Some images of different parameter settings of Knowledge Based Imaging are visually compared with Second-Harmonic Imaging, Fundamental Imaging and Bandwidth Imaging. Changing parameters of Knowledge Based Imaging can make the image look similar to both Bandwidth Imaging and Fundamental Imaging.
147

Internationalization of French firms within the medical technology industry

Griot, Clémence January 2010 (has links)
French SMEs within the medical technology industry follow an internationalization pattern which cannot completely be explained by traditional internationalization models. Going abroad is not a strategy to overcome challenges inherent to the medical technology industry. Instead, it is the positive consequence of their merge with internationalized firms, or an opportunity offered by their network.
148

A Fully Integrated Microneedle-based Transdermal Drug Delivery System

Roxhed, Niclas January 2007 (has links)
Patch-based transdermal drug delivery offers a convenient way to administer drugs without the drawbacks of standard hypodermic injections relating to issues such as patient acceptability and injection safety. However, conventional transdermal drug delivery is limited to therapeutics where the drug can diffuse across the skin barrier. By using miniaturized needles, a pathway into the human body can be established which allow transport of macromolecular drugs such as insulins or vaccines. These microneedles only penetrate the outermost skin layers, superficial enough not to reach the nerve receptors of the lower skin. Thus, microneedle insertions are perceived as painless. The thesis presents research in the field of microneedle-based drug delivery with the specific aim of investigating a microneedle-based transdermal patch concept. To enable controllable drug infusion and still maintain an unobtrusive and easy-to-use, patch-like design, the system includes a small active dispenser mechanism. The dispenser is based on a novel thermal actuator consisting of highly expandable microspheres. When actuated, the microspheres expand into a liquid reservoir and, subsequently, dispense stored liquid through outlet holes. The microneedles are fabricated in monocrystalline silicon by Deep Reactive Ion Etching. The needles are organized in arrays situated on a chip. To allow active delivery, the microneedles are hollow with the needle bore-opening located on the side of the needle. This way, the needle can have a sharp and well-defined needle tip. A sharp needle is a further requirement to achieve microneedle insertion into skin by hand. The thesis presents fabrication and evaluation of both the microneedle structure and the transdermal patch as such. Issues such as penetration reliability, liquid delivery into the skin and microneedle packaging are discussed. The microneedle patch was also tested and studied in vivo for insulin delivery. Results show that intradermal administration with microneedles give rise to similar insulin concentration as standard subcutaneous delivery with the same dose rate. / QC 20100623
149

Distansuppföljning av ICD-patienter : En hälsoekonomisk utvärdering

Sandås, Therese, Karlström, Micaela January 2009 (has links)
Uppsatsens syfte är att undersöka vilka ekonomiska effekter införandet av distansuppföljning för ICD-patienter har ur ett samhällsperspektiv. Delsyftet är att identifiera ekonomiska argument och kvalitativa aspekter för och emot införandet av tjänsten distansuppföljning. Författarna har kommit fram till ett antal slutsatser. Att införa distansuppföljning som uppföljningsmetod för ICD-patienter istället för konventionella återbesök på sjukhus innebär stora kostnadsbesparingar. Nettonuvärdet uppgår till drygt 268 miljoner kronor efter femton år. Vid tidsperiodens slut erhålls en kostnadsbesparing på cirka 35,6 procent. De ekonomiska fördelarna överstiger kostnaderna redan efter ett år, och hela investeringskostnaden återfås efter sju år. Kvalitativa argument som talar för distansuppföljning är tidsbesparingar, förenklad uppföljning, bättre övervakning och att patienterna upplever en större trygghet.
150

Development and Evaluation of an Inertial Sensor for Gait Analysis

Nutti, Björn January 2006 (has links)
Hasomed GmbH, a German company in the Field of medicine technology, intends to introduce a gait analysis system on the market. The system includes an inertial sensor which collects data used for generating movement patterns of the feet. This thesis describes the development and evaluation of a new version of the sensor, aimed at minimizing costs, maximizing performance and facilitating production. Algorithms used in the gait analysis system are sensitive to noise. Noise sources and precautions taken in order to minimize noise levels are described and discussed. By minimizing the physical size of analogue electronics blocks, static noise and occasional high frequency components were substantially reduced. New features including internal temperature sensors, firmware update via serial interface, self-test functions and a wireless link were implemented. Additional improvements are e.g. lower power consumption and an extension of the interface from 2 to 256 (theoretical limit) attached devices. By reducing the number of included components and PCB (Printed Circuit Board) layers, together with use of components that do not require advanced soldering techniques, easier and cheaper production was obtained. Research and development presented in this thesis resulted in a sensor with overall good performance and new features.

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