Dortmund, Univ., Diss., 2002. / Computerdatei im Fernzugriff.

Abstract Intraoperative surgery has created a need to develop new kinds of surgical tools. Also, the development of imaging techniques and devices has precipitated the need. Robotics plays an increasingly important role in surgery. A robot can yield better accuracy, smaller movements and, as a result, a faster healing process than a normal operation would require for recovering and healing larger cuts in the human body. Magnetic resonance imaging, MRI, is one of the safest imaging techniques, and it has excellent soft tissue contrast. In the last few years, MRI has become a more frequently-used technique in the intraoperative surgery, such as the biopsy. Brain biopsies in particular are easier to perform by the help of MRI. When designing a robot, or any other mechatronic device, for an MR environment, it becomes vital to consider its appropriateness, i.e., electric and magnetic compatibility with MRI. The latter is a notion related to the surgical procedure and the magnetic field being applied. It implies that instrumentation has to be more compatible with MR in higher magnetic fields. In this study, an MR-compatible robot was developed to work inside open MRI equipment. The MR compatibility of the robot was evaluated, using the testing method evolved during the study. The method helps select the suitable material and parts for mechatronic devices operating under MRI. Most notably, this work also devised and introduced new types of sensors to achieve better MR compatibility of the equipment. As a result of this research, a suitable material was developed for the robot's body as well as for the sensors, actuators and tools. Furthermore, it was deduced that some sensors and the control system when powered can not be used in the MR scanner at all. A further result was that the movement of a robotic arm does not disturb image quality in any way. The testing method developed in this research helps address the compatibility issues arising from the use of any device that works in MRI. The testing method can be used for magnetic fields of different strengths. The robot and the control parts constructed in the research were tested under a 0.23-T open MRI scanner. The results show which materials and fibre optics provide a highly MR compatible solution for an MRI environment. The results also show that normal electric motors can not be driven close to the magnetic field while imaging.

Bakgrund: Magnetresonanstomografi (MRT) är en modalitet inom radiografi, som blir allt vanligare tack vare sin överlägsna mjukvävnadskontrast och avsaknad av joniserande strålning. Eftersom MRT kräver att patienten ligger stilla i ett trångt utrymme är det vanligt att patienten upplever klaustrofobirelaterad ångest. Detta kan leda till att undersökningar avbryts och det leder till stor kostnad för vården samt besvär för patienten. Syfte: Syftet med denna litteraturstudie var att belysa ickefarmakologiska faktorer som kan förebygga klaustrofobirelaterad ångest hos vuxna. Metod: Sökningen av artiklar gjordes i databaserna Pubmed, CINAHL, Sciencedirect och PsychINFO. 10 artiklar inkluderades i litteraturstudiens resultat och analyserades av författarna. Resultat: Författarna fann fem olika ickefarmakologiska faktorer, som visade sig minska klaustrofobirelaterad ångest. Dessa faktorer är; utökad information, avslappningsövningar, förbättrat bemötande, patientens positionering och magnetkamerans design. Slutsats: Författarnas resultat visade att det finns ett flertal ickefarmakologiska faktorer, som kan användas för att minska klaustrofobirelaterad ångest.   Nyckelord: MR, Klaustrofobi, Ångest, Vuxna.

Bakgrund: En magnetkameraundersökning är en relativt säker diagnostisk metod då ingen joniserande strålning används, till skillnad från konventionell röntgen, vid framställandet av bilder. Trots detta finns ändå risker att ta hänsyn till, vissa gällande för alla patienter. För neonatala barn, prematura och fullgångna, skiljer sig dessa risker åt och därmed även neonatalpersonalens och röntgensjuksköterskans möjlighet att tillgodose barnets patientsäkerhet. Syfte: litteraturstudien syftar till att därför beskriva specifika riskfaktorer som påverkar patientsäkerheten vid undersökning med MR av fullgångna och prematura barn. Metod: vetenskapliga artiklar söktes i databaserna PubMed, Cinahl och Medline, varav åtta kvantitativa artiklar valdes ut efter kvalitetsgranskning. Resultat: Efter analys av dessa åtta artiklar utmärkte sig fyra kategorier som redovisades i resultatet; bildkvalitet, hypotermi, nedsatt saturation och narkosmedel. Resultatet visade även att användandet av en mr-kompatibel kuvös ytterligare påverkade patientsäkerheten positivt. Konklusion: Bildkvalitet, hypotermi, nedsatt saturation och narkosmedel är specifika riskfaktorer som visar sig viktiga att ta hänsyn till vid beaktande av patientsäkerheten för prematura och fullgångna neonatala barn. Nyckelord: MRI, magnetkamera, neonatal, patientsäkerhet, risker / Background: MRI is a relatively safe diagnostic method with non-ionizing radiation used, as is not the case in conventional radiography. Despite this there are still risks to take into account, some common to all patients. For neonates, premature and full-term, these risks differ, and thereby also affect the neonatal staff and the radiographer's ability to meet the child's special need of patient safety. Purpose: This study aims to describe specific risk factors that affect patient safety during examination with MRI, regarding the full term and preterm neonatal child. Method: scientific articles were searched in PubMed, Cinahl and Medline, eight quantitative articles were selected for quality review. Results: After analysis of these eight articles, four categories were recognized and distinguished; image quality, hypothermia, low oxygen saturation, and anesthetics. The results also showed that the use of an MR-compatible incubator further impacted patient safety positively. Conclusion: Image quality, hypothermia, low oxygen saturation and anesthetics are specific risk factors that need to take into account when considering the patient safety in preterm and full-term neonates. Keywords: magnetic resonance imaging, infant premature, patient safety

No description available.

Bakgrund: Intracerebral hjärnblödning (ICH) står för omkring 20 % av alla cerebrovaskulära sjukdomar och uppkommer oftast snabbt, vanligtvis i samband med aktivitet. Är blödningen stor kan hjärnans mittstrukturer flytta på sig, vilket i värsta fall kan leda till koma eller döden. Datortomografi (CT) och magnetisk resonanstomografi (MR) är idag de vanligaste radiologiska undersökningsmetoderna för att upptäcka en ICH.   Syfte: Att jämföra CT och MR vid diagnosticering av ICH, för att ta reda på respektive undersökningsmetods för- och nackdelar och därför kunna avgöra vilken metod som är att föredra vid diagnosticering av ICH.   Metod: En litteraturstudie baserad på artiklar funna i databasen PubMed genomfördes, där åtta artiklar hittades vid sökning. Två artiklar hittades vid en manuell sökning.   Resultat: MR är bra i ett tidigt stadium vid ICH. Gradient echos (GRE) roll vid MR verkar vara bra vid undersökning av ICH, men är likvärdig med CT, däremot tyder det på att GRE är mer noggrann än CT vad gäller mätning av blödningens volym, då den mätta volymen visar sig bli större med GRE än med CT däremot kan CT vara mindre tillförlitlig vid små ICH.   Konklusion: Denna litteraturstudies resultat tyder på att MR är en säkrare diagnostisk metod vid ICH än CT, däremot krävs större studier inom detta område för att kunna dra en definitiv slutsats.

No description available.

Universiẗat, Diss., 2002--Dortmund.

The diploma thesis deals with testing of sports car suspension. The aim is the testing of fast magnetorheological damper in semiactive suspension that corresponds to quarter car model. The fast magnetorheological damper has a response time 2 ms. If the response time is short enough (order of units miliseconds) it is possible (based on earlier simulations) to achieve improvement of driving safety (better stability of force of tyre on roadway) and comfort (reduction of vibrations). The thesis proves this statement with series of experiments.

Este trabalho de tese apresenta novas evidências experimentais que ajudam no conhecimento atual das propriedades de transporte em semicondutores orgânicos, aprofundando o conhecimento dos processos de condução dependentes de spin em dispositivos eletrônicos baseados nestes materiais. O trabalho apresentado pode ser dividido em dois temas principais, o primeiro relacionado ao aumento das qualidades espectroscópicas da técnica de ressonância magnética detectada eletricamente (RMDE) por meio de um estudo da dependência do sinal vetorial de RMDE em função da freqüência do campo magnético de modulação. O segundo tema, encontrase relacionado aos efeitos de campos magnéticos externos na condutividade de semicondutores orgânicos. Através de uma análise de fase cuidadosa do sinal vetorial de RMDE foi demonstrado que o espectro de RMDE de diodos orgânicos emissores de luz (OLEDs) baseados em alumínio (III) 8-hidroxiquinolina (\'Alq IND. 3\') pôde ser separado em dois sinais componentes com fatores-g de: \'g IND. h\'= 2,007 e \'g IND. e\'= 2,0035. O espectro de RMDE de OLEDs baseados em \'Alq IND. 3\' foi atribuído ao processo de formação de éxcitons, e os sinais componentes foram atribuídos ao par precursor do éxciton, um à ressonância em ânions de \'Alq IND. 3\', enquanto que o outro a estados catiônicos no \'Alq IND. 3\'. Foi demonstrado que a utilização de diferentes freqüências de modulação de campo magnético aumenta a resolução temporal do sistema de detecção de RMDE, não influenciando os valores dos parâmetros espectroscópicos dos sinais. Desta forma, foi observado que os sistemas ou processos dependentes de spin diferentes que dão origem ao sinal de RMDE de OLEDs baseados em \'Alq IND. 3\', têm uma diferença entre os tempos de resposta menor que 6.0 x \'10 POT. -7\'s. Neste trabalho se propõe um modelo de circuito para simular a origem do sinal de RMDE de OLEDs baseados em \'Alq IND. 3\'. Os resultados deste modelo têm uma grande concordância com os resultados experimentais, observando-se que os dois sistemas ou processos de spin diferentes que dão origem ao sinal, podem ser representados por uma combinação paralela de capacitâncias e \"resistores\" que tomam a forma de funções gaussianas em condições de ressonância magnética. A generalidade deste modelo indica que ele poderia ser utilizado em outros problemas de transporte dependentes de spin de outros dispositivos eletrônicos orgânicos, inorgânicos ou híbridos (inorgânico-orgânico). Resultados de estudos de RMDE de OLEDs baseados em \'Alq IND. 3\', dopados e não dopados, em baixas temperaturas (até 100 K), mostraram que no OLED dopado com rubreno pode existir um mecanismo de formação de éxcitons similar ao já observado para o OLED dopado com DCM-TPA, indicando que o mecanismo de formação de éxcitons no OLED dopado com rubreno seria uma reação direta entre um elétron no \'Alq IND. 3\' com um buraco aprisionado no dopante. Foram observados efeitos do campomagnético na condutividade de dispositivos baseados em semicondutores orgânicos demonstrando a ocorrência do fenômeno de magneto-resistência (MR) em dispositivos orgânicos e híbridos (orgânico-inorgânico). Estes estudos mostraram que a melhor forma de detecção destes efeitos é através do monitoramento da resistência em função do tempo sob a aplicação de campos magnéticos externos. Para os dispositivos baseados em \'Alq IND. 3\', OLEDs dopados e não dopados e um dispositivo e-only, foi observada somente MR negativa, enquanto que para um dispositivo h-only foi observado um novo efeito quase constante e positivo. Para campos magnéticos aplicados de até 1 T, os dispositivos unipolares mostraram baixos efeitos de campo magnético na condutividade alcançando MR de até 0,08%, enquanto que os OLEDs mostraram efeitos maiores alcançando MR de até 3,2%. Apesar do mecanismo exato que origina os efeitos de campo magnético na condutividade de semicondutores orgânicos ainda permanecer desconhecido, os resultados apresentados neste trabalho indicam que este fenômeno não está relacionado com a formação de éxcitons. / This thesis presents new experimental evidences that can improve the current knowledge of the transport properties in organic semiconductors, particularly the spin dependent conduction processes in electronic devices based in those materials. This work can be divided in two main subjects, the first one related to the increasing in the spectroscopic qualities of the electrically detected magnetic resonance (EDMR) technique and the second one related to the external magnetic field effects in the conductivity of the organic semiconductors. Using a careful phase analysis of the vectorial EDMR signal it was demonstrated that the aluminium (III) 9-hydroxyquinoline (\'Alq IND. 3\')-based organic light emitting diodes (OLEDs) spectrum cam be separated in two component signais with different g-factors: \"G IND. h\'= 2,007 and \'g IND. e\'= 2,0035. The EDMR spectrum of \'Alq IND. 3\'-based OLEDs was attributed to the exciton formation process and the component signals were attributed to the resonance in \'Alq IND. 3\' anions (electrons) and in cationic states (holes) into \'Alq IND. 3\'. It was demonstrated that the use of different magnetic field modulations frequencies (MFMF) improves the temporal resolution of the EDMR system detection. It observed that the difference in the lifetime of the two EDMR signal components is smaller than 6.0x\'10 POT -7\'s. We proposed a novel circuit model to explain the observed EDMR signals. Results from this model are in agreement with the experimentalresults showing that the EDMR signal of \'Alq IND. 3\'-based OLEDS comes fromtwo different spin systems that can be represented by a parallel combination of capacitance and resistances which acquires a Gaussian form is magnetic resonance conditions. The simplest circuit model indicates that it can be used in other spin-dependent transport problems of different electronic devices (organic, inorganic or hybrid) studied by EDMR experiments. Results from a EDMR investigation of the effects of dye doping on spin dependent exciton formation in \'Alq IND. 3\'-based OLEDs at low temperatures (up to 100 K) showed that the Rubrene dye doped \'Alq IND. 3\'-based OLEDs presents a similar mechanism for exciton formation that the DCM--TPA doped OLED indicating that the recombination occurs by a direct reaction between an electron in the \'Alq IND. 3\' and a hole into the dopant. Magnetic field effects in the conductivity of organic semiconductors based devices were observed, showing the existence of the magnetoresistance (MR) phenomena in both organic and hybrids (organic-inorganic) devices. The studies showed that the best way to detect this effects is by monitoring the resistance as a function of time under the application of different magnetic field pulses. Only negative magnetoresistance was observed for the \'Alq IND. 3\'-based devices: undoped and dye doped OLEDs and an electron only device. A very small, positive and almost constant MR was observedin the hole-only device. For the unipolar devices were observed small magnetic field effects in the conductivity reaching a MR= 0.08%. The OLEDs showed bigger effects reaching a MR= 3.2%. Despite the exact mechanism that origins the magnetic field effects in the conductivity of organic semiconductors remains unknown the results presented in this thesis indicates that this phenomena is not related to the exciton formation.