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Ultraljud är en användbar teknik för att utföra undersökningar i realtid samtidigt som det ej utsätter patienter för joniserad strålning. Det finns en potential för ultraljud att fylla ett gap på dagens marknad inom medicinsk avbildning då den kan tillämpas i mindre format. Utgångspunkten för detta arbete var att se om det går att konstruera en miniultraljudstransducer i ett tillräckligt litet format så det enkelt kan appliceras på kroppen och på så sätt kunna utföra kontinuerliga mätningar vid områden av intresse. En omfattande genomsökning av liknande projekt och vad som finns på dagens marknad genomfördes. Resultatet av studien och marknadsanalysen var att det inte fanns liknande produkter på marknaden idag, utan mycket var fortfarande under ett utvecklingsstadie. Riktningen som valdes för projektet var att konstruera en piezoelektrisk transducer. Komponenter som ingår i en sådan konstruktion är ett backing layer, en piezoelektrisk kristall, ett matching layer och elektroder som genererar ström till kristallen. Ett problem som uppstod under arbetet var konstruktionens matching layer dels då den tjocklek som eftersträvs är så liten att de blir svårt att ta fram utan mekaniska hjälpmedel, dels då den inte kunde förinstalleras på det piezoelektriska elementet. Miniultraljudstransducern testades vid två mättillfällen. Första mättillfället resulterade i signal som var svår att tyda. Det antas bero på att totalreflektion uppstått samt att instrumenten ej var korrekt inställda. Vid mättillfälle två, där samtliga fel från första mätningen hade åtgärdats så kunde den förväntade signalen avläsas. / Ultrasound is a medical imaging method which is done in real time without the drawback of exposing the patients for ionizing radiation. This method has great potential of filling a gap that exists withing the medical imaging market due to its possibility of being greatly reduced in size. The starting point for this work was to see if it would be possible to create a mini ultrasound transducer which is small enough for it to easily be connected to the body where it can perform continuous measurements at areas of interest. An extensive literature study of similar projects and market analysis was carried out. This resulted in that there were no similar products on the market, due to it still being under development and researched. The direction which was chosen was to design a piezoelectric transducer. Components included in such a construction consists of a backing layer, piezoelectric crystals, matching layer and electrodes which will supply the crystal with current. A problem that arose during the work was constructions matching bearings partly because the thickness sought is so small that they become difficult to produce without mechanical aids, partly because it could not be pre-installed on the piezoelectric element.The mini ultrasound transducer was tested on two measuring occasions. The first measurement opportunity resulted in a signal that was difficult to decipher. It is assumed that this is due to the fact that total reflection occurred since the construction was not completely optimally designed, so there was room for air between the crystal and the matching layer and that the instruments were not set correctly. At measurement occasion two, where all errors from the first measurement had been rectified the expected signal could be read.

This dissertation examines brain lateralization and interhemispheric asymmetry patterns found in youths with Attention-Deficit / Hyperactivity Disorder (ADHD). Prior research groups have found mixed findings with respect to left and right hemisphere alterations from ADHD subjects using structural magnetic resonance imaging. In these investigations, we propose the use of Asymmetry Index (AI), a subject-specific metric that quantifies the extent of brain asymmetry and allows each subject to serve as their own control, thus reducing variability when pooling across different sites. We compare AI metric with laterality across volumetric, surface area, thickness, morphology, and white matter measures in order to characterize the ADHD brain over the course of neurodevelopment, psychotropic therapy, and behavioral presentations. Linear mixed effects models were characterized to account for individual differences and maturation. We reproduce the findings across several regional and international data consortiums that contain both cross-sectional and longitudinal ADHD neuroimaging data. Structural asymmetry group differences were more significant than lateralized comparisons across a number of volumetric and white matter measures, confirming asymmetry is robust at detecting differences between healthy controls and ADHD brains. However, the effects of medication and behavioral phenotypes failed to reproduce significant alterations across symmetry measures. We discuss these implications in light of recent evidence of possible neuroprotective features of ADHD. Future work may investigate the extent to which these brain asymmetry differences are causal or compensatory. Although structural AI is unlikely to provide a useful biomarker for ADHD, a deeper understanding of these asymmetry patterns could lead to better profiling of the clinical diagnostics and to personalized treatments.

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<p>The use of both percutaneous and tunnelled central venous catheters in hospitalized patients has increased markedly over the last decade (Camp-Sorrell, 1990). With this increase, there is a clinical need to have an occlusive central line dressing to maintain a barrier to possible site contamination. This randomized control trial examined the use of the transparent dressing OpSite Wound (Smith and Nephew-Ine.) versus the ransparent dressing LV. 3000 (Smith & Nephew Inc.) in its ability to maintain an occlusive central line dressing. The study took place at Chedoke-McMaster Hospitals McMaster Division from June 1991 to September 1991. Adult medical-surgical patients who had a central line in place for longer than 48 hours were eligible for the study. Twenty five central lines were randomized to either the control group (OpSite Wound) or the experimental group (LV. 3000) An independent assessor saw all study patients daily to document dressing adhesiveness and the number of dressing changes performed. Analysis showed that the LV. 3000 dressing was changed every 5.5 days as opposed to the OpSite Wound dressing that was changed every 2.6 days. This difference was both statistically and clinically significant Analysis also showed that the dressings covering central lines with no intravenous in-line attachment (pigtail) were changed more frequently than the dressings covering central lines with an attached pigtail. This difference was also statistically significant The LV. 3000 dressing therefore, provides an occlusive central line dressing that is changed one-half the number of times that the OpSite Wound dressing is changed, or in other words, the OpSite. Wound dressing is changed twice as often as the I.V. 3000 dressing when used on central lines.</p> / Master of Health Sciences (MSc)

Thesis (M.B.A.)--University of Hong Kong, 1993.