Die Kombination von Positronen-Emissions-Tomographie (PET) und Röntgen-Computertomographie (CT) in Form moderner PET/CT-Geräte ermöglicht die Nutzung der CT-Information zur Korrektur der Photonenschwächung in der PET. Allerdings können Bewegungen, die zum Beispiel durch die Atmung hervorgerufen werden können, zu einer fehlerhaften Schwächungskorrektur führen. Die Einführung von zeitlich aufgelöster Bildgebung für beide Modalitäten (4D-PET/4D-CT) ermöglicht nicht nur die Auflösung von periodischen Bewegungen, sondern auch die Reduktion dieser Fehler in der Schwächungskorrektur. Dazu werden die einzelnen Datensätze des 4D-PET, die jeweils einer bestimmten Bewegungsphase entsprechen, mit dem entsprechenden CT-Datensatz dieser Atemphase schwächungskorrigiert. In der vorliegenden Arbeit wurde diese phasenkorrelierte Schwächungskorrektur des 4D-PET mit dem 4D-CT am Universitästsklinikum Dresden installierten PET/CT ermöglicht und anhand von Phantomexperimenten mit anderen Schwächungskorrekturmethoden für 4D-PET verglichen. Dazu musste zunächst die Aufnahme von 4D-CT an dem verwendeten PET/CT ermöglicht und dessen Synchronität mit dem 4D-PET hergestellt werden. Außerdem wurde ein vorhandenes Atemphantom so modifiziert, dass es typische Bewegungen von Bronchialkarzinomen in zwei Dimensionen und mit zwei möglichen Atemmustern simuliert. Die phasenkorrelierte Schwächungskorrektur führte zu einer quantitativ korrekten Wiederherstellung des Aktivitätsvolumens, der darin enthaltenen Aktivität sowie der Bewegungsamplitude und stellt somit die beste der hier verglichenen 4D-PET-Schwächungskorrekturmethoden dar. Diese Ergebnisse lassen vermuten, dass die phasenkorrelierte Schwächungskorrektur auch bei klinischer Anwendung eine signifikante Verbesserung in oben genannten Punkten darstellt. Dies sollte in Zukunft an Patientendaten überprüft werden. / The combination of Positron Emission Tomography (PET) and Computed Tomography (CT) in one device allows the use of CT-information for attenuation correction in PET. Though motion, for example induced by respiration, can cause inaccurate attenuation correction. The implementation of time-resolved imaging methods for both modalities (4D-PET/4D-CT) enables not only the resolution of motion but also the reduction of artifacts caused by attenuation correction. Therefore, the single datasets of the 4D-PET that are related to a individual respiratory phase, are attenuation corrected with the corresponding dataset of the 4D-CT. This phase correlated attenuation correction of the 4D-PET with the 4D-CT was implemented at the PET/CT installed at the Universitätsklinikum Dresden. For that purpose the acquisition of 4D-CT was implemented at the PET/CT and its synchronisation with the 4D-PET was verified. Furthermore the new attenuation correction method was compared with other attenuation correction methods by performing phantom experiments. Therefore an exisisting respiratory phantom had to be modified to perform typical lung tumor motion in two dimensions with two possible patterns of respiration. The phase correlated attenuation correction leads to a quantitatively correct restauration of the activity volume, its total activity and its motion amplitude. Compared with other correction methods, the phase correlated attenuation correction shows the best results in all examined criteria. This findings suggest that the clinical application of the phase correlated attenuation correction will also lead to a significant improvement in all mentioned points. This has to be verified by analyzing patient data.

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The objective of this work is to improve the diagnostic quality and reduce the radiation dose of computed tomography coronary angiography (CTCA) imaging by developing gating techniques based on signals derived from cardiac motion, rather than the currently used electrocardiogram (ECG), to more reliably trigger data acquisition during periods of cardiac quiescence. Because the ECG is an indication of electrical activity, it is a surrogate marker of the mechanical state of the heart. Therefore, gating based on a signal derived directly from cardiac motion using either echocardiography or seismocardiography (SCG) should prove better at detecting and predicting periods of cardiac quiescence. Improved gating would permit the use of CTCA in more instances to either replace or determine the necessity of invasive and expensive CCAs. This work presents novel methods for detecting and predicting cardiac quiescence. Quiescence is detected as periods of minimal velocity from echocardiography, computed tomography (CT), and SCG. Identified quiescent periods are used to develop and evaluate techniques for predicting cardiac quiescence using echocardiography and SCG. Both echocardiography and SCG are shown to be more accurate for predicting quiescent periods than ECG. Additionally, the average motion during quiescent periods predicted by echocardiography and SCG is shown to be lower than those predicted using only ECG. Lastly, cardiac CT reconstructions from quiescent phases predicted by a commercial CT scanner were compared to the optimal quiescent phases calculated using the CT quiescence detection methods presented in this work. The diagnostic quality of the reconstructions from the optimal phases was found to be higher than that of the phases predicted by the CT scanner, suggesting that there is the potential for marked improvement in CTCA performance through more accurate cardiac gating.

This thesis explores the lives of women in a small group of families in the Nottinghamshire elite between 1720 and 1820. A close reading of family papers, gives access to the minutiae of female life and it is from these small details that the attitudes, activities and responsibilities of elite women are constructed. Drawing on the distinct historiographies of women and gender, and of the elite, the evidence produced by this sharply-focused approach is used to explore women's formal and informal roles, and the specific ways in which they were fulfilled, in the domestic, social, economic and political life of the elite. Consideration is first given to attitudes towards girls within the family and to how childhood experience contributed to the construction of elite womanhood. An assessment of the level of convergence between family and individual interests in the matter of marital choices is followed by an exploration of the weight of domestic responsibility experienced by women within the family, as wives, mothers and housekeepers. Attention turns to assessing the extent of female engagement with political, economic and social life, in the pursuit of personal and family interests. The narratives of women and their families illuminate how the female elite balanced the particular mix of subordination and privilege conferred upon them by gender and status. The range of activities in which they engaged and the multifaceted nature of that engagement demonstrate that throughout the eighteenth century women at all levels of the Nottinghamshire elite worked to support the ethos of elite pre-eminence in many small but cumulatively significant ways.

The following PhD thesis will explore the connection between autobiography and myth of origin: On the one hand, I am concerned with the ways in which women autobiographers rewrite classical myths of origin; on the other hand, I contend that autobiography itself is a myth of origin, a recreation of the forces that created the narrator. Throughout this thesis, I will develop two main themes: the first is the use of myth as a framework for autobiographical writing. This is possible because of myth's characteristic double focus on the universal and on the particular version, the historical context. Myth allows feminist autobiographers to connect themselves to universal truths from which they are barred by patriarchal tradition and to carve out their own, highly personal version. The second theme is that the autobiographers depict the origin as the core of the self and utterly Other. First, the narrator has to rely on the stories of other people, or a 'family memory'. Second, the past can be seen as connected to or leaving traces in the present; at the same time, it can be completely Other and incompehensible. Third, the autobiographical I is often cut off from her origins, and a constructive return that integrates the past and the present self is only possible through a deliberate act of mythmaking: It is mythmaking and storytelling that provides a connection between self and Other. I hope to make a contribution to feminist theory of autobiography as well as to feminist theory. Reading autobiography as myth of origin approaches the persistent problem of the relationship between the historical author and the autobiographical self. Moreover, I will explore the the specific relation between women and origins, and address the necessity for feminist theory to develop a framework where self and Other are intimately connected.

This project assesses the four dimensional computed tomography (4DCT) capabilities of the Philips Brilliance Big Bore CT scanner (Philips Medical Systems, Cleveland, OH). A mechanical phantom imparts clinically relevant motions to acrylic spheres of various diameters. The size, shape, and position of these spheres, as measured with 4DCT, are compared to their true size, shape, and position. An evaluation of image quality is also performed. Maximum discrepancies between physical and imaged volumes, for all sphere sizes and motion ranges, did not exceed 2.6 mm (mean = 1.2 mm, standard deviation = 0.4 mm). For approximately tissue equivalent density objects, mean CT# in 4DCT images differed from those in standard clinical thoracic images by only a few Hounsfield units. Measured geometric precision along with the accuracy of mean CT#s observed in 4DCT phase images indicate that 4DCT is an appropriate imaging technique for treatment planning. / Medical Physics

Knowledge of anatomy is an elementary step towards the understanding of the human body. First used by Alphonse Bertillon as an identification system, anthropometry refers to the measurements of human individuals. In orthopaedics, comparative analysis is widely used in the understanding of morphological variance due to races, sex and pathological conditions. The characterization of bone and joint geometry has also been a foundation of modern surgical implant design. Traditional anthropometric studies rely on physical measurements by means of osteometric table. Recent advancements of 3-D imaging modalities and image processing techniques have empowered more fine-grained anthropometric characterization. The inspiration for the study is: - the understanding of anatomy originating from the clinical domain have shown to contribute to undesirable inconsistency in the image processing domain. - the difficulty of existing automated anthropometric methodology in handling pathological femur. - the tedious amount of manual and subjective work involved with the increasing amount of high resolution imaging data. The aim of the study is to: - develop a consistent and robust methodology in accurate extraction of anthropometric parameters on the femur. - increase the level of automation on the process of anthropometric parameter extraction. With the bridging of anthropometry and the image processing disciplines, a robust methodology of anthropometric parameter extraction with high level of automation was developed, implemented and tested. A dataset comprised of femoral CT scans of 19 healthy Australian, 10 healthy Japanese, 15 Japanese diagnosed with primary or secondary hip osteoarthritis and 20 adult sheep was utilized for testing. Intra-class correlation and Cronbach's α were extensively employed to evaluate the intra-rater, interrater and repeated scans consistency of the proposed methodology. High correlation values (mean > 0.95) were noted suggesting a high consistency of the methodology. All healthy and osteoarthritis human datasets were processed successfully. With the structural similarity between the sheep and human femur, the robustness was further demonstrated by accurate processing of the sheep dataset without the need of any modification of the underlying methodology. The methodology proposed is highly automated and requires very few user interactions in the parameter extraction stage.

Tübingen, Univ., Diss., 2005.

As everyone knows, cancer is one of the greatest health enemies of mankind and became a major public health problem all over the world. Moreover, lung cancer is the most common global cancer leading to more than 1.3 million estimated deaths annually worldwide. Breast cancer is the most common cancer and the 2nd leading cause of death from in women in the US, Canada, and China. Therefore an instrument for the early diagnosis and monitoring of cancers in areas such as lung and breast is immensely important and necessary. The cadmium zinc telluride (CZT) semiconductor is a kind of novel radiation detector that can provide detailed information about spatial position. Also, the energy resulting from interactions between the radiation and the CZT material can also be assessed giving this type of detector added value in disease evaluation. A great deal of work on CZT detectors has been done for breast CT scanning. Furthermore, the CZT detector is also a potential solution for problems in lung cancer CT evaluation where the lack of energy information and high radiation exposure are less than ideal. Since sub-millimetre spatial resolution is required for post-contrast thoracic CT assessment, and $100~\mu m$ or better is critical for breast CT, the investigation of spatial resolution for CZT detectors is essential. In this thesis, the interactions within CZT detectors were analyzed. The influence of different configurations, including adjustment of anode size, gap size, detector thickness and bias voltage, were discussed. Next the methods to evaluate two kinds of signals (collected and transit signals), are provided in Chapter~2. In Chapter~3, an intensity difference method and an intensity ratio method for estimating the sub-pitch spatial resolution were described in detail. Finally, a detector spatial resolution between $10~\mu m$ and $20~\mu m$ was achieved using the collecting signal intensities ratio method and a $4~mm$ thick CZT detector with gap size of $g=50~\mu m$ and bias voltage of $V=300V$. Future work should focus on the contributions from characteristic X-rays emitted from cadmium and tellurium atoms. Also, the work presented was only on pixelated arrays and further assessment of cross-strip electrode detectors could also be of benefit. Lastly based on simulations done in this thesis all photons were assumed to strike the cathode at 90 degrees. Future work should also include non-orthogonal directions for photons. / Thesis / Master of Applied Science (MASc)

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