Die Positronen-Emissions-Tomographie (PET) bei der Schwerionentherapie ist eine wichtige Methode zur Qualitätskontrolle in der Tumortherapie mit Kohlenstoffionen. Die vorliegende Arbeit beschreibt die Verbesserungen des PET-Verfahrens, wodurch sich in der Folge präzisere Aussagen zur Dosisapplikation treffen lassen. Aufbauend auf den Grundlagen (Kap. 2) werden die Neuentwicklungen in den drei darauf folgenden Abschnitten (Modellierung des Abbildungsprozesses bei der PET, Streukorrektur für PET bei der Schwerionentherapie, Verarbeitung der rekonstruierten PET-Daten) beschrieben. Die PET-Methode bei der Schwerionentherapie basiert auf dem Vergleich zwischen den gemessenen und vorausberechneten Aktivitätsverteilungen. Die verwendeten Modelle in der Simulation (Erzeugung der Positronenemitter, deren Ausbreitung, der Transport und der Nachweis der Annihilationsquanten) sollten so präzise wie möglich sein, damit ein aussagekräftiger Vergleich möglich wird. Die Genauigkeit der Beschreibung der physikalischen Prozesse wurde verbessert und zeiteffiziente Algorithmen angewendet, die zu einer erheblichen Verkürzung der Rechenzeit führen. Die erwarteten bzw. die gemessenen räumlichen Radioaktivitätsverteilungen werden mit einem iterativen Verfahren rekonstruiert [Lau99]. Die gemessenen Daten müssen hinsichtlich der im Messobjekt auftretenden Comptonstreuung der Annihilationsphotonen korrigiert werden. Es wird ein geeignetes Verfahren zur Streukorrektur für die Therapieüberwachung vorgeschlagen und dessen Realisierung beschrieben. Zur Einschätzung der Güte der Behandlung wird die gemessene und die simulierte Aktivitätsverteilung verglichen. Dazu wurde im Rahmen der vorliegenden Arbeit eine Software entwickelt, das die rekonstruierten PET-Daten visualisiert und die anatomischen Informationen des Röntgentomogramms mit einbezieht. Nur durch dieses Auswerteverfahren war es möglich, Fehler im physikalischen Strahlmodell aufzudecken und somit die Bestrahlungsplanung zu verbessern.

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Introdução: A técnica clássica para o implante coclear é realizada por meio de mastoidectomia seguida de timpanotomia posterior. O acesso pela fossa craniana média provou ser uma alternativa valiosa, embora seja usada para o implante coclear, ainda sem normatização. Objetivo: Descrever um novo acesso pela fossa craniana média que expõe o giro basal da cóclea para o implante coclear. Métodos: Estudo anatômico de ossos temporais. Foram dissecados 50 ossos temporais. A cocleostomia foi realizada mediante um acesso via fossa craniana média, na porção mais superficial do giro basal da cóclea, usando o plano meatal e seio petroso superior como as principais referências anatômicas. Foi determinada a distância entre os pontos de referência, o ângulo entre o plano meatal e a cocleostomia, e a distância entre esta estrutura e a janela redonda. Foi realizada tomografia computadorizada em 5 dos ossos temporais utilizados neste estudo. Resultados: Em todos os 50 ossos temporais, apenas a porção mais superficial do giro basal da cóclea foi aberta e tanto as escalas timpânica como a vestibular foram visualizadas. As distâncias médias ± DP, menores e maiores, entre a cocleostomia e o plano meatal foram estimadas em 2,48±0,88mm e 3,11±0,86mm, respectivamente. A distância média da cocleostomia até a janela redonda foi de 8,38±1,96mm, e daquela até o seio petroso superior 9,19±1,59mm. As distâncias médias, menores e maiores, entre a cocleostomia e o eixo longo do plano meatal a partir da sua porção mais proximal foram estimadas em 6,63±1,38mm e 8,2±1,43mm, respectivamente. O valor médio do ângulo entre a cocleostomia e o plano meatal foi igual a 22,54±7,400. As tomografias computadorizadas demonstraram a inserção do feixe de eletrodos por meio do giro basal da cóclea até o seu ápice em todas as peças submetidas a este exame. Conclusão: A técnica proposta para identificar o giro basal da cóclea é simples e confiável. Igualmente, permite a visualização da escala timpânica e a inserção do feixe de eletrodos do implante coclear através desta câmara / Introduction: The classic technique for cochlear implantation uses mastoidectomy followed by posterior tympanotomy. The middle cranial fossa approach has proved to be a valuable alternative for cochlear implantation, although the standardization of this technique is still needed. Objectives: To describe a novel approach through the middle cranial fossa for exposing the cochlear basal turn for cochlear implantation. Materials And Methods: Anatomical temporal bone study. Fifty temporal bones were dissected. A cochleostomy was performed via a middle fossa approach on the most superficial part of the cochlear basal turn, using the meatal plane and superior petrous sinus as the main landmarks. The distance between the landmarks, the angle between the cochleostomy and the meatal plane, and the distance between this structure and the round window were measured. A computed tomography was performed on 5 of the studied temporal bones. Results: In all 50 temporal bones, only the superficial portion of the cochlear basal turn was uncovered. The cochlear exposure allowed both the scala tympani and vestibule to be exposed. The mean ± SD minor and major distances between the cochleostomy and the meatal plane were estimated to be 2.48±0.88mm and 3.11±0.86mm, respectively. The mean distance from the cochleostomy to the round window was 8.38±1.96mm, and that to the superior petrosal sinus was 9.19±1.59mm. The mean minor and major distances between the cochleostomy and the long axis of the meatal plane from its most proximal portion were estimated to be 6.63±1.38mm and 8.29±1.43mm, respectively. The mean angle between the cochleostomy and the meatal plane was 22.54±7.400. The computed tomography of all 5 temporal bones demonstrated the insertion of the implant array from the cochlear basal turn towards its apex. Conclusion: The proposed technique for identifying the cochlear basal turn is simple and trustworthy. Additionally, it enables visualization of the scala tympani, facilitating the insertion of the cochlear implant array through this chamber

Introdução: A técnica clássica para o implante coclear é realizada por meio de mastoidectomia seguida de timpanotomia posterior. O acesso pela fossa craniana média provou ser uma alternativa valiosa, embora seja usada para o implante coclear, ainda sem normatização. Objetivo: Descrever um novo acesso pela fossa craniana média que expõe o giro basal da cóclea para o implante coclear. Métodos: Estudo anatômico de ossos temporais. Foram dissecados 50 ossos temporais. A cocleostomia foi realizada mediante um acesso via fossa craniana média, na porção mais superficial do giro basal da cóclea, usando o plano meatal e seio petroso superior como as principais referências anatômicas. Foi determinada a distância entre os pontos de referência, o ângulo entre o plano meatal e a cocleostomia, e a distância entre esta estrutura e a janela redonda. Foi realizada tomografia computadorizada em 5 dos ossos temporais utilizados neste estudo. Resultados: Em todos os 50 ossos temporais, apenas a porção mais superficial do giro basal da cóclea foi aberta e tanto as escalas timpânica como a vestibular foram visualizadas. As distâncias médias ± DP, menores e maiores, entre a cocleostomia e o plano meatal foram estimadas em 2,48±0,88mm e 3,11±0,86mm, respectivamente. A distância média da cocleostomia até a janela redonda foi de 8,38±1,96mm, e daquela até o seio petroso superior 9,19±1,59mm. As distâncias médias, menores e maiores, entre a cocleostomia e o eixo longo do plano meatal a partir da sua porção mais proximal foram estimadas em 6,63±1,38mm e 8,2±1,43mm, respectivamente. O valor médio do ângulo entre a cocleostomia e o plano meatal foi igual a 22,54±7,400. As tomografias computadorizadas demonstraram a inserção do feixe de eletrodos por meio do giro basal da cóclea até o seu ápice em todas as peças submetidas a este exame. Conclusão: A técnica proposta para identificar o giro basal da cóclea é simples e confiável. Igualmente, permite a visualização da escala timpânica e a inserção do feixe de eletrodos do implante coclear através desta câmara / Introduction: The classic technique for cochlear implantation uses mastoidectomy followed by posterior tympanotomy. The middle cranial fossa approach has proved to be a valuable alternative for cochlear implantation, although the standardization of this technique is still needed. Objectives: To describe a novel approach through the middle cranial fossa for exposing the cochlear basal turn for cochlear implantation. Materials And Methods: Anatomical temporal bone study. Fifty temporal bones were dissected. A cochleostomy was performed via a middle fossa approach on the most superficial part of the cochlear basal turn, using the meatal plane and superior petrous sinus as the main landmarks. The distance between the landmarks, the angle between the cochleostomy and the meatal plane, and the distance between this structure and the round window were measured. A computed tomography was performed on 5 of the studied temporal bones. Results: In all 50 temporal bones, only the superficial portion of the cochlear basal turn was uncovered. The cochlear exposure allowed both the scala tympani and vestibule to be exposed. The mean ± SD minor and major distances between the cochleostomy and the meatal plane were estimated to be 2.48±0.88mm and 3.11±0.86mm, respectively. The mean distance from the cochleostomy to the round window was 8.38±1.96mm, and that to the superior petrosal sinus was 9.19±1.59mm. The mean minor and major distances between the cochleostomy and the long axis of the meatal plane from its most proximal portion were estimated to be 6.63±1.38mm and 8.29±1.43mm, respectively. The mean angle between the cochleostomy and the meatal plane was 22.54±7.400. The computed tomography of all 5 temporal bones demonstrated the insertion of the implant array from the cochlear basal turn towards its apex. Conclusion: The proposed technique for identifying the cochlear basal turn is simple and trustworthy. Additionally, it enables visualization of the scala tympani, facilitating the insertion of the cochlear implant array through this chamber

Made available in DSpace on 2011-05-04T12:36:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2009 / O acidente vascular cerebral (AVC) é uma das principais causas de morbidade e mortalidade, tanto em países desenvolvidos quanto nos menos desenvolvidos. No Brasil essa patologia tem sido responsável por mais óbitos que a doença coronária. Alguns aspectos do cuidado com o AVC são comuns para todos os tipos patológicos, mas existem diferenças fundamentais no tratamento de pacientes com AVC isquêmico e AVC hemorrágico. Assim, o cuidado com o paciente com sintomas de AVC depende muito de um diagnóstico rápido e acurado do processo patológico em andamento. Nesse contexto, o exame de imagem do cérebro por tomografia computadorizada pode proporcionar um diagnóstico acurado da natureza e da extensão do problema, e identificar se ele é isquêmico ou hemorrágico. Todavia, tomógrafos computadorizados (TC) são equipamentos de custo relativamente alto, o que se torna um problema diantedo quadro comum de escassez de recursos econômicos para os sistemas de saúde. Isso reflete a necessidade de se ofertar essa tecnologia para a população, da forma mais racional e equitativa possível. Nesse cenário, por intermédio do levantamento de informações em bancos de dados públicos, sobre internação, mortalidade, população, índice de desenvolvimento humano e oferta de TC; e da utilização de sistemas de informação geográfica para o mapeamento desses parâmetros no território nacional; procurou-se caracterizar a oferta de TC no Brasil e a sua adequação às necessidades de saúde dos pacientes com AVC. Os resultados encontrados no universo pesquisado mostram uma distribuição geográfica de TC pouco equitativa, e uma concentração da oferta dessa tecnologia nos municípios mais populosos e de melhor situação socioeconômica. A metodologia adotada permitiu, ainda, observar uma associação da condição socioeconômica e do local de residência com a internação em municípios com serviços de saúde mais bem equipados para o cuidado com o AVC, o que caracteriza uma situação de desigualdade geográfica e social no acesso aos serviços de saúde para o atendimento ao AVC. / Stroke is one of the main causes of morbidity and mortality not only in developed countries but also in developing ones. In Brazil, this pathology has been responsible for more deaths than heart disease. Some aspects of the treatment of stroke are common to all the pathologic types but there are fundamental differences in the care of patients with ischemic stroke and of those with hemorrhagic stroke. Thus, treatment of patients with stroke symptoms is highly dependent on a fast and accurate diagnostic of the pathologic process in progress. In this context, the image exam of the brain through computerized tomography can offer a correct diagnostic of the nature and extension of the problem, as well as identify if it is ischemic or hemorrhagic. However, computerized tomography scanners are relatively expensive equipments, what makes it a problem in the face of the common lack of economic resources to health systems. This reflects the necessity of offering this technology to population, in the most rational and equitable way as possible. In this scenery, through the information picked in public data bases about hospital admission, mortality, population, human developing index and supply of computerized tomography; and also the use of geographic information systems to the mapping of these parameters in national territory; it has been characterized the supply of computerized tomography in Brazil and its association to the health needs of the patients with stroke. The results show inequity in geographic distribution of computerized tomography scanners as well as a concentration of this technology in the most populous cities and those with a better economic situation. The methodology that has been adopted also allowed us to observe the association of the social-economic condition and place of residence, with hospital admissions in cities with better equipped health services for treating stroke, characterizing a situation of social and geographic inequality in the access to stroke adequate diagnosis and treatment.

<p>Трауматско оштећење мозга (ТОМ) настаје услед дејства спољашње мехничке силе на кранијум и ендокранијални садржај, које се карактерише привременим или трајним неуролошким оштећењем, функционалном онеспособљеношћу или психосоцијалном неприлагођеношћу. Најчешће коришћени предиктори исхода су године повређеног, иницијални Гласгов кома скор (ГКС), статус зеница на пријему, време протекло од момента повређивања до неурохируршког збрињавања, удружене повреде, хипоксија, хипертензија и налаз компјутерско-томографског снимања. Основни циљ истраживања је израда алгоритма ургентног лечења трауматског можданог оштећења и дизајн скале за рану предикцију исхода ТОМ уз додатну анализу појединих фактора на пријему (ГКС, неуролошки налаз, радиолошки налаз, клинички симптоми). Спроведено је ретроспективно и проспективно истраживање којим је обухваћено 568 испитаника који су у периоду од 1.6.2018. до 31.05.2019. лечени унутар Клиничког центра Војводине у Новом Саду због трауматске озледе мозга. Узорак је чинило 34,3% жена и 65,7 % мушкараца. Старосна структура узорка је од 18-96 године (М=56,56; SD=20,17). Свим пацијентима је по пријему начињена радиолошка дијагностика компјутеризованом томографијом (ЦТ), начињен је детаљан физикални и неуролошки преглед, те је детаљно узета анамнеза. Нотирани су следећи подаци: витални параметри (артеријски крвни притисак, сатурација крви кисеоником), статус и повреде других система органа, знаци повређивања главе и врата. За неуролошки преглед је коришћена ГКС скала. За ЦТ преглед је нотирано присуство интракранијалних трауматских лезија и прелома лобање. Резултати овог истраживања указали су на неопходност пажљивог разматрања бројних фактора (радиолошких и клиничких) који се могу испољити већ на самом пријему. Иако ЦТ има висок појединачни допринос предвиђању исхода у моделу са више варијабли није се издвојио као значајан. Пацијенти који су имали дужи период између времена протеклог од момента повређивања до неурохируршког збрињавања имали су бољи исход лечења. Предпоставља се да су пацијенти који су стизали раније у здравствену установу имали тежа трауматска оштећења мозга и самим тим исход је био лошији, док су пацијенти са благим оштећењима долазили касније управо из разлога што манифестације проблема нису биле хитне. Ротердам скала се издвојила добром дискриминативном способношћу када се користи као изолован инструмент. Као најјачи предиктори издвојили су се следећи предиктори: нису показане цистерне на ЦТ-у, присутан САХ, померање више од 5 mm, присутан мали субдурални хематом, присутна велика контузија, примена антиагрегациона тераpија. Успешност предвиђања на основу новог модела је 96%. Резултати студије се могу искористити за боље разумевање ТОМ у смислу лакшег решавања дијагностичких дилема и терапијских, креирање ефикаснијих дијагностичких протокола и прецизније процене исхода након повређивања. Предикција исхода лечења је од великог значаја како би се благовермено направио алгоритам лечења и праћења ових пацијената.</p> / <p>Traumatsko oštećenje mozga (TOM) nastaje usled dejstva spoljašnje mehničke sile na kranijum i endokranijalni sadržaj, koje se karakteriše privremenim ili trajnim neurološkim oštećenjem, funkcionalnom onesposobljenošću ili psihosocijalnom neprilagođenošću. Najčešće korišćeni prediktori ishoda su godine povređenog, inicijalni Glasgov koma skor (GKS), status zenica na prijemu, vreme proteklo od momenta povređivanja do neurohirurškog zbrinjavanja, udružene povrede, hipoksija, hipertenzija i nalaz kompjutersko-tomografskog snimanja. Osnovni cilj istraživanja je izrada algoritma urgentnog lečenja traumatskog moždanog oštećenja i dizajn skale za ranu predikciju ishoda TOM uz dodatnu analizu pojedinih faktora na prijemu (GKS, neurološki nalaz, radiološki nalaz, klinički simptomi). Sprovedeno je retrospektivno i prospektivno istraživanje kojim je obuhvaćeno 568 ispitanika koji su u periodu od 1.6.2018. do 31.05.2019. lečeni unutar Kliničkog centra Vojvodine u Novom Sadu zbog traumatske ozlede mozga. Uzorak je činilo 34,3% žena i 65,7 % muškaraca. Starosna struktura uzorka je od 18-96 godine (M=56,56; SD=20,17). Svim pacijentima je po prijemu načinjena radiološka dijagnostika kompjuterizovanom tomografijom (CT), načinjen je detaljan fizikalni i neurološki pregled, te je detaljno uzeta anamneza. Notirani su sledeći podaci: vitalni parametri (arterijski krvni pritisak, saturacija krvi kiseonikom), status i povrede drugih sistema organa, znaci povređivanja glave i vrata. Za neurološki pregled je korišćena GKS skala. Za CT pregled je notirano prisustvo intrakranijalnih traumatskih lezija i preloma lobanje. Rezultati ovog istraživanja ukazali su na neophodnost pažljivog razmatranja brojnih faktora (radioloških i kliničkih) koji se mogu ispoljiti već na samom prijemu. Iako CT ima visok pojedinačni doprinos predviđanju ishoda u modelu sa više varijabli nije se izdvojio kao značajan. Pacijenti koji su imali duži period između vremena proteklog od momenta povređivanja do neurohirurškog zbrinjavanja imali su bolji ishod lečenja. Predpostavlja se da su pacijenti koji su stizali ranije u zdravstvenu ustanovu imali teža traumatska oštećenja mozga i samim tim ishod je bio lošiji, dok su pacijenti sa blagim oštećenjima dolazili kasnije upravo iz razloga što manifestacije problema nisu bile hitne. Roterdam skala se izdvojila dobrom diskriminativnom sposobnošću kada se koristi kao izolovan instrument. Kao najjači prediktori izdvojili su se sledeći prediktori: nisu pokazane cisterne na CT-u, prisutan SAH, pomeranje više od 5 mm, prisutan mali subduralni hematom, prisutna velika kontuzija, primena antiagregaciona terapija. Uspešnost predviđanja na osnovu novog modela je 96%. Rezultati studije se mogu iskoristiti za bolje razumevanje TOM u smislu lakšeg rešavanja dijagnostičkih dilema i terapijskih, kreiranje efikasnijih dijagnostičkih protokola i preciznije procene ishoda nakon povređivanja. Predikcija ishoda lečenja je od velikog značaja kako bi se blagovermeno napravio algoritam lečenja i praćenja ovih pacijenata.</p> / <p>Traumatic brain injury (TBI) Is defined as temporary or permanent neurological damage, functional disability or psychosocial inadaptability occurring due to effects of external mechanical force to brain and cranium. Mostly used predictors are age, Glasgow coma scale score, pupillary reactivity, time from injury to neurosurgical intervention, combined injuries, hypoxia, hypertension and computed tomography (CT) findings. Basic goal of this research was to analyse TBI and design early outcome prediction scale together with the analysis of individual factors on admission (GCS, neurological status, radiological findings). This research was both retro and prospective and included 568 patients treated for TBI at Clinical centre of Vojvodina in Novi Sad from 01.06.2018. to 31.05.2019. Sample was made out of 34,3% females and 65,7 % males aged from 18 to 96 years ( M=56,56; SD=20,17). All patients had CT diagnostics preformed upon admission, had undergone detailed general and neurological examination and patient&rsquo;s history was taken. Physical examination included: vitals (arterial blood pressure, blood oxygenation), status and injuries of other organs, signs of injury to head and neck. GCS scale was used for neurological examination Computed tomography (CT) included presence of intracranial lesions and skull fractures. Results of this research showed importance of careful observation of multiple factors (radiological and clinical) that can be present at the time of admission. Despite CT having high individual predictive power for outcome, in multiple variable model it was not significant. Patients with longer time elapsed to treatment had better outcome. It is assumed that patients who arrived shortly after injury had severe TBI thus having worse outcome, while patients suffering from mild TBI arrived later and thus had better outcome right because their symptoms of TBI were not very symptomatic. Rotterdam scale showed good disciminative power. The strongest predictors were: CT absence of cisterns, present subarachnoid haemorrhage, midline shift over 5mm, presence of small subdural haematoma, presence of large contusion, presence of antiaggregational therapy. Predictive power based on primary model was 96%. Results of this study can be used for better understanding of TBI in order to solve some diagnostic dilemma, create more efficient diagnostic protocols and facilitate more precise outcome assessment after TBI. Prediction of treatment outcome is very important in order to timely design treatment algorithm of treatment and follow up of TBI patients.</p>

<div>The mechanical behaviors of different kinds of biological tissues, including muscle tissues, cortical bones, cancellous bones and skulls, were studied under various loading conditions to investigate their strain-rate sensitivities and loading-direction dependencies. Specifically, the compressive mechanical behaviors of porcine muscle were studied at quasi-static (<1/s) and intermediate (1/s─10^2/s) strain rates. Both the compressive and tensile mechanical behaviors of human muscle were investigated at quasi-static and intermediate strain rates. The effect of strain-rate and loading-direction on the compressive mechanical behaviors of human frontal skulls, with its entire sandwich structure intact, were also studied at quasi-static, intermediate and high (10^2/s─10^3/s) strain rates. The fracture behaviors of porcine cortical bone and cancellous bone were investigated at both quasi-static (0.01mm/s) and dynamic (~6.1 m/s) loading rates, with the entire failure process visualized, in real-time, using the phase contrast imaging technique. Research effort was also focused on studying the dynamic fracture behaviors, in terms of fracture initiation toughness and crack-growth resistance curve (R-curve), of porcine cortical bone in three loading directions: in-plane transverse, out-of-plane transverse and in-plane longitudinal. A hydraulic material testing system (MTS) was used to load all the biological tissues at quasi-static and intermediate loading rates. Experiments at high loading rates were performed on regular or modified Kolsky bars. Tomography of bone specimens was also performed to help understand their microstructures and obtain the basic material properties before mechanical characterizations. Experimental results found that both porcine muscle and human muscle exhibited non-linear and strain-rate dependent mechanical behaviors in the range from quasi-static (10^(-2)/s─1/s) to intermediate (1/s─10^2/s) loading rates. The porcine muscle showed no significant difference in the stress-strain curve between the along-fiber and transverse-to-fiber orientation, while it was found the human muscle was stiffer and stronger along fiber direction in tension than transverse-to fiber direction in compression. The human frontal skulls exhibited a highly loading-direction dependent mechanical behavior: higher ultimate strength, with an increasing ratio of 2, and higher elastic modulus, with an increasing ratio of 3, were found in tangential loading direction when compared with those in the radial direction. A transition from quasi-ductile to brittle compressive mechanical behaviors of human frontal skulls was also observed as loading rate increased from quasi-static to dynamic, as the elastic modulus was increased by factors of 4 and 2.5 in the radial and tangential loading directions, respectively. Experimental results also suggested that the strength in the radial direction was mainly depended on the diploë porosity while the diploë layer ratio played the predominant role in the tangential direction. For the fracture behaviors of bones, straight-through crack paths were observed in both the in-plane longitudinal cortical bone specimens and cancellous bone specimens, while the cracks were highly tortuous in the in-plane transverse cortical bone specimens. Although the extent of toughening mechanisms at dynamic loading rate was comparatively diminished, crack deflections and twists at osteon cement lines were still observed in the transversely oriented cortical bone specimens at not only quasi-static loading rate but also dynamic loading rate. The locations of fracture initiations were found statistical independent on the bone type, while the propagation direction of incipient crack was significantly dependent on the loading direction in cortical bone and largely varied among different types of bones (cortical bone and cancellous bone). In addition, the crack propagation velocities were dependent on crack extension over the entire crack path for all the three loading directions while the initial velocity for in-plane direction was lower than the other two directions. Both the cortical bone and cancellous bone exhibited higher fracture initiation toughness and steeper R-curves at the quasi-static loading rate than the dynamic loading rate. For cortical bone at a dynamic loading rate (5.4 m/s), the R-curves were steepest, and the crack surfaces were most tortuous in the in-plane transverse direction while highly smooth crack paths and slowly growing R-curves were found in the in-plane longitudinal direction, suggesting an overall transition from brittle to ductile-like fracture behaviors as the osteon orientation varies from in-plane longitudinal to out-of-plane transverse, and to in-plane transverse eventually.</div>

Im Rahmen der vorliegenden Dissertationsschrift „Semi-quantitative röntgentomographische Untersuchungen zur Biodistribution von magnetischen Nanopartikeln in biologischem Gewebe“ wurden tomographische Untersuchungen an biologischen Objekten durchgeführt. Bei diesen Objekten handelt es sich um Gewebeproben nach minimal-invasiven Krebstherapien wie zum Beispiel magnetischem Drug Targeting und magnetischer Wärmebehandlung. Der Erfolg dieser Therapien ist sowohl abhängig von der korrekten Verteilung der magnetischen Nanopartikel als auch von der Tatsache, dass diese in der Zielregion in einer ausreichenden Menge vorhanden sind. Das Vorliegen dieser beiden Voraussetzungen ist in der vorliegenden Arbeit untersucht worden. Dabei lag der Schwerpunkt der Arbeit auf der Quantifizierung von magnetischem Material in unterschiedlichen biologischen Gewebeproben mittels Röntgenmikrocomputertomographie (XµCT). Für diesen Zweck wurde ein Kalibrationssystem mit speziellen Phantomen entwickelt, mit dessen Hilfe eine Nanopartikelkonzentration einem Grauwert voxelweise zugewiesen werden kann. Mit Hilfe der Kalibration kann der Nanopartikelgehalt sowohl in monochromatischen als auch in polychromatischen tomographischen Daten im Vergleich zu magnetorelaxometrischen Ergebnissen mit wenigen Prozent Abweichung ermittelt werden. Trotz Polychromasie und damit einhergehenden Artefakten können 3-dimensionale röntgentomographische Datensätze mit einer geringfügigen Konzentrationsabweichung im Vergleich zur quantitativen Messmethode Magnetorelaxometrie semi-quantitativ ausgewertet werden. / The success of the minimal invasive cancer therapies, called magnetic drug targeting and magnetic heating treatment, depends strongly on the correct distribution of the magnetic nanoparticles on one side. On the other side it depends on the fact that a sufficient amount of magnetic nanoparticles carrying drugs is accumulated in the target region. To study whether these two requirements are fulfilled motivates this PhD thesis „Semi-quantitative X-ray-tomography examinations of biodistribution of magnetic nanoparticles in biological tissues“. The analysis of the distribution of the magnetic nanoparticles in tumours and other tissue examples is realized by means of X-ray-micro computer tomography (XμCT). The work focuses on the quantification of the magnetic nanoparticles in different biological tissue samples by means of XµCT. A calibration of the tomographic devices with adequate phantoms, developed in the frame of this work, opens now the possibility to analyze tomographic data in a semi-quantitative manner. Thus, the nanoparticle concentration can be allocated voxel-wise to the grey values of the three-dimensional tomographic data. With the help of calibration of the tomography equipments used, polychromatic as well as monochromatic three-dimensional representations of objects can be analyzed with regard to the biodistribution of magnetic nanoparticles as well as with regard to their quantity. The semi-quantitative results have been compared with results obtained with a quantitative measurement method magnetorelaxometry (MRX). Thereby a good agreement of the semi-quantitative and quantitative data has been figured out.

The majority of UK’s intermediate level radioactive waste is currently stored in 316L and 304L austenitic stainless steel containers in interim storage facilities for permanent disposal until a geological disposal facility has become available. The structural integrity of stainless steel canisters is required to persevere against environmental degradation for up to 500 years to assure a safe storage and disposal scheme. Hitherto existing severe localised corrosion observances on real waste storage containers after 10 years of exposure to an ambient atmosphere in an in-land warehouse in Culham at Oxfordshire, however, questioned the likelihood occurrence of stress corrosion cracking that may harm the canister’s functionality during long-term storage. The more corrosion resistant duplex stainless steel grade 2205, therefore, has been started to be manufactured as a replacement for the austenitic grades. Over decades, the threshold stress corrosion cracking temperature of austenitic stainless steels has been believed to be 50-60°C, but lab- and field-based research has shown that 304L and 316L may suffer from atmospheric stress corrosion cracking at ambient temperatures. Such an issue has not been reported to occur for the 2205 duplex steel, and its atmospheric stress corrosion cracking behaviour at low temperatures (40-50°C) has been sparsely studied which requires detailed investigations in this respect. Low temperature atmospheric stress corrosion cracking investigations on 2205 duplex stainless steel formed the framework of this PhD thesis with respect to the waste storage context. Long-term surface magnesium chloride deposition exposures at 50°C and 30% relative humidity for up to 15 months exhibited the occurrence of stress corrosion cracks, showing stress corrosion susceptibility of 2205 duplex stainless steel at 50°C.The amount of cold work increased the cracking susceptibility, with bending deformation being the most critical type of deformation mode among tensile and rolling type of cold work. The orientation of the microstructure deformation direction, i.e. whether the deformation occurred in transverse or rolling direction, played vital role in corrosion and cracking behaviour, as such that bending in transverse direction showed almost 3-times larger corrosion and stress corrosion cracking propensity. Welding simulation treatments by ageing processes at 750°C and 475°C exhibited substantial influences on the corrosion properties. It was shown that sensitisation ageing at 750°C can render the material enhanced susceptible to stress corrosion cracking at even low chloride deposition densities of ≤145 µm/cm². However, it could be shown that short-term heat treatments at 475°C can decrease corrosion and stress corrosion cracking susceptibility which may be used to improve the materials performance. Mechanistic understanding of stress corrosion cracking phenomena in light of a comprehensive microstructure characterisation was the main focus of this thesis.

Im Rahmen der vorliegenden Dissertationsschrift „Semi-quantitative röntgentomographische Untersuchungen zur Biodistribution von magnetischen Nanopartikeln in biologischem Gewebe“ wurden tomographische Untersuchungen an biologischen Objekten durchgeführt. Bei diesen Objekten handelt es sich um Gewebeproben nach minimal-invasiven Krebstherapien wie zum Beispiel magnetischem Drug Targeting und magnetischer Wärmebehandlung. Der Erfolg dieser Therapien ist sowohl abhängig von der korrekten Verteilung der magnetischen Nanopartikel als auch von der Tatsache, dass diese in der Zielregion in einer ausreichenden Menge vorhanden sind. Das Vorliegen dieser beiden Voraussetzungen ist in der vorliegenden Arbeit untersucht worden. Dabei lag der Schwerpunkt der Arbeit auf der Quantifizierung von magnetischem Material in unterschiedlichen biologischen Gewebeproben mittels Röntgenmikrocomputertomographie (XµCT). Für diesen Zweck wurde ein Kalibrationssystem mit speziellen Phantomen entwickelt, mit dessen Hilfe eine Nanopartikelkonzentration einem Grauwert voxelweise zugewiesen werden kann. Mit Hilfe der Kalibration kann der Nanopartikelgehalt sowohl in monochromatischen als auch in polychromatischen tomographischen Daten im Vergleich zu magnetorelaxometrischen Ergebnissen mit wenigen Prozent Abweichung ermittelt werden. Trotz Polychromasie und damit einhergehenden Artefakten können 3-dimensionale röntgentomographische Datensätze mit einer geringfügigen Konzentrationsabweichung im Vergleich zur quantitativen Messmethode Magnetorelaxometrie semi-quantitativ ausgewertet werden. / The success of the minimal invasive cancer therapies, called magnetic drug targeting and magnetic heating treatment, depends strongly on the correct distribution of the magnetic nanoparticles on one side. On the other side it depends on the fact that a sufficient amount of magnetic nanoparticles carrying drugs is accumulated in the target region. To study whether these two requirements are fulfilled motivates this PhD thesis „Semi-quantitative X-ray-tomography examinations of biodistribution of magnetic nanoparticles in biological tissues“. The analysis of the distribution of the magnetic nanoparticles in tumours and other tissue examples is realized by means of X-ray-micro computer tomography (XμCT). The work focuses on the quantification of the magnetic nanoparticles in different biological tissue samples by means of XµCT. A calibration of the tomographic devices with adequate phantoms, developed in the frame of this work, opens now the possibility to analyze tomographic data in a semi-quantitative manner. Thus, the nanoparticle concentration can be allocated voxel-wise to the grey values of the three-dimensional tomographic data. With the help of calibration of the tomography equipments used, polychromatic as well as monochromatic three-dimensional representations of objects can be analyzed with regard to the biodistribution of magnetic nanoparticles as well as with regard to their quantity. The semi-quantitative results have been compared with results obtained with a quantitative measurement method magnetorelaxometry (MRX). Thereby a good agreement of the semi-quantitative and quantitative data has been figured out.