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<p>To date, image localization of mobile tumors prior to radiation delivery has primarily been confined to 2D and 3D technologies, such as fluoroscopy and 3D cone-beam CT (3D-CBCT). Due to the limited information from these images, larger volumes of healthy tissue are often irradiated in order to ensure the radiation field encompasses the entirety of the target motion. Since the overarching goal of radiation therapy is to deliver maximum dose to cancerous cells and simultaneously minimize the radiation delivered to healthy surrounding tissues, it would be ideal to use 4D imaging to obtain time-resolved volume images of the tumor motion during respiration. </p><p>4D-CBCT imaging has been previously investigated, but has not yet seen large clinical translation due to the obstacles of long acquisition time and large image radiation dose. Furthermore, 4D-CBCT currently requires the use of external surrogates to correlate the patient's respiration with the image acquisition process. This correlation has been under question by a multitude of studies demonstrating the uncertainties that exist between the surrogate and the actual motion of the internal anatomy. Errors in the correlation process may result in image artifacts, which could potentially lead to reconstructions with inaccurate target volumes, thereby defeating the purpose of even using 4D-CBCT. </p><p>It is therefore the aim of this dissertation to initially highlight an additional limitation of using 3D-CBCT for imaging respiratory motion and thereby reiterate the need for 4D-CBCT imaging in the treatment room, develop a simple and efficient technique to achieve markerless, self-sorted 4D-CBCT and finally to comprehensively evaluate its robustness across a variety of potential clinical scenarios with a digital human phantom. </p><p>People often spend a longer period of time exhaling as compared with inhaling, and some do so in an extremely disproportionate manner. To demonstrate the disadvantage of using 3D-CBCT in such instances, a dynamic thorax phantom was imaged with a large variety of simulated and patient-derived respiratory traces of ratios of time spent in the inspiration phase versus time spent in the expiration phase (I/E ratio). Canny edge detection and contrast measures were employed to compare the internal target volumes (ITVs) generated per profile. The results revealed that an I/E ratio of less than one can lead to potential underestimation of the ITV with the severity increasing as the inspiration becomes more disproportionate to the expiration. This occurs because of the loss of contrast in the inspiration phase, due to the fewer number of projections acquired there. The measured contrast reduction was as high as 94% for small targets (0.5 cm) moving large amplitudes (2.0 cm) and still as much as 22.3% for large targets (3.0 cm) moving small amplitudes (0.5 cm). This is alarming because the degraded visibility of the target in the inspiration phase may inaccurately impact the alignment of the planning ITV with that of the FB-CBCT and thereby affect the accuracy of the localization and consequent radiation delivery. These potential errors can be avoided with the use of 4D-CBCT instead, to form the composite volume and serve as the verification ITV for alignment.</p><p>In order to delineate accurate target volumes from 4D-CBCT phase images, it is crucial that the projections be properly associated with the patient's respiration. Thus, in order to improve previously developed 4D-CBCT techniques, the basics of Fourier Transform (FT) theory were utilized to extract the respiratory signal directly from the acquired projection data. Markerless, self-sorted 4D-CBCT reconstruction was achieved by developing methods based on the phase and magnitude information of the Fourier Transform. Their performance was subsequently compared to the gold standard of visual identification of peak-inspiration projections. Slow-gantry acquired projections of two sets of physical phantom data with sinusoidal respiratory cycles of 3 and 6 seconds as well as three patients were used as initial evaluation of the feasibility of the Fourier technique. Quantitative criteria consisted of average difference in respiratory phase (ADRP) and percentage of projections assigned within 10% respiratory phase of the gold standard (PP10). For all five projection datasets, the results supported feasibility of both FT-Phase and FT-Magnitude methods with ADRP values less than 5.3% and PP10 values of 87.3% and above. </p><p>Because the technique proved to be promising in the initial feasibility study, a more comprehensive evaluation was necessary in order to assess the robustness of the technique across a larger set of possibilities that may be encountered in the clinic. A 4D digital XCAT phantom was used to generate an array of respiratory and anatomical variables that affect the performance of the technique. The respiratory variables studied included: inspiration to expiration ratio, respiratory cycle length, diaphragmatic motion amplitude, AP chest wall expansion amplitude, breathing irregularities such as baseline shift and inconsistent peak-inspiration amplitude, as well as six breathing profiles derived from cine-MRI images of three healthy volunteers and three lung cancer patients. The anatomical variables studied included: male and female patient size (physical dimension and adipose content), body-mass-index (BMI) category, tumor location, and percentage of the lung in the field-of-view (FOV) of the projection data. CBCT projections of each XCAT phantom were then generated. Additional external imaging factors such as image noise and detector wobble were added to select cases with different percentages of lung in the projection FOV to investigate any effects on the robustness. FT-Phase and FT-Magnitude were each applied and quantitatively compared to the gold standard. Both methods proved to be robust across the studied scenarios with ADRP<10% and PP10>90%, when incorporating minor modifications to region-of-interest (ROI) selection and/or low-frequency location to certain cases of diaphragm amplitude and lung percentage in the FOV of the projection (for which a method may have previously struggled). Nevertheless, in the instance where one method initially faltered, the other method prevailed and successfully identified peak-inspiration projections. This is promising because it suggests that the two methods provide complementary information to each other. To ensure appropriate clinical adaptation of markerless, self-sorted 4D-CBCT, perhaps an optimal integration of the two methods can be developed.</p> / Dissertation

As the role of technology within warfare continues to increase, it is important to investigate whether or not the consequences of these weapons are being adequately considered. The use of new weapons technologies, such as Unmanned Combat Aerial Vehicles and Precision Guided Munitions, have been both praised and condemned within the war in Afghanistan. Although praised as saving civilian lives due to the precision capabilities of the weaponry there are consistent civilian deaths attributed to these weapons systems. This study examines debates regarding new weapons technologies that have been utilised during the war in Afghanistan. Current literature regarding emerging weapons technology is examined in order to identify key debates. The literature was recognised as falling predominantly within three perspectives - strategy, law and ethics. By identifying the key debates within each perspective it is possible to identify where these debates overlap or diverge. This research concludes that the introduction of counterinsurgency strategy to modern warfare has led to an increasing concern with the ethical and legal dimensions of the debate surrounding new weapons technology.

What influences the evolution of junior school reading programmes in the classrooms of beginning teachers? Of all the classroom skills required of beginning teachers, those contributing to the implementation of an effective instructional reading programme perhaps represent some of the most complex and sophisticated challenges that will be encountered. Add to this the critical importance to young children of successfully learning to read and the very obvious picture of reading progress revealed by modern assessment practices, and the result is an aspect of teaching that can assume a position of significant focus. This is especially true for teachers working with junior school children. This study investigated the current practices of three junior school teachers during their first two years teaching, how these practices have evolved over time and identifies the factors that have influenced each teacher. Participants' stories were gathered during individual interviews to establish current practices and these were compared with a typical sample of classroom reading instruction that had been captured on video prior to the initial interviews. Each teacher also participated in an individual follow up interview during which they were able to observe the sample video excerpt and comment reflectively upon their practice in the light of their observations. This study found that developing effective junior school reading programmes generated considerable angst for these beginning teachers. While they were able to draw upon preservice preparation when articulating their intentions, the transition from the abstractions of theory to the realities of classroom practice challenged their teaching skills in this fledgling stage of their career. Despite an apparent commitment to guided reading as emphasized in pre-service literacy courses, each participant implemented round robin reading as their initial teaching strategy. In order to implement reading pedagogy as advocated within their pre-service experiences, the emergence of a professional conscience appears to have been critical. The way that teachers' understanding of literacy acquisition consolidates is greatly influenced by their practical classroom experiences and the personal capacity that they bring to the teaching role. The findings of this study support Berliner (1994) and Huberman (1989) because each of the teachers could be placed on a trajectory of teacher development. However stage related views of professional development do not fully reflect the complexity of individuals combined with the uniqueness of their contexts. The broader perspective highlighted in the work of Nias (1989) provided a framework more accommodating of the realities encountered during this study.

This dissertation develops a robust, data-driven localization methodology based on the integration of matched field processing with compressed sensing ℓ1 recovery techniques and scale transform signal processing. The localization methodology is applied to an ultrasonic guided wave structural health monitoring system for detecting, locating, and imaging damage in civil infrastructures. In these systems, the channels are characterized by complex, multi-modal, and frequency dispersive wave propagation, which severely distort propagating signals. Acquiring the characteristics of these propagation mediums from data represents a difficult inverse problem for which, in general, no readily available solution exists. In this dissertation, we build data-driven models of these complex mediums by integrating experimental guided wave measurements with theoretical wave propagation models and ℓ1 sparse recovery methods from compressed sensing. The data-driven models are combined with matched field processing, a localization framework extensively studied for underwater acoustics, to localize targets in complex, guided wave environments. The data-driven matched field processing methodology is then refined, through the use of the scale transform, to achieve robustness to environmental variations that distort guided waves. Data-driven matched field processing is experimentally applied to an ultrasound structural health monitoring system to detect and locate damage in aluminum plate structures.

This thesis presents a theoretical study of thermoelastic guided waves in cylinders in the context of Lord-Shulman generalized theory of thermoelasticity. Two different methods were formulated to study dispersion relations in infinite cylinders. One of them is a Semi Analytical Finite Element (SAFE) method and the other is an analytical method. In the SAFE method, the dispersion equation has been formulated as a generalized eigenvalue problem by treating radial displacement and temperature with a one dimensional finite element model through the thickness of the cylinder. In the analytical method, displacement potentials are introduced to obtain the dispersion relations of guided wave modes. This method is applicable to isotropic cylinders and has been developed primarily to cross check the SAFE formulation. Frequency spectra obtained by both methods for an isotropic cylinder have shown excellent agreement with each other. Since the SAFE method can be used for an anisotropic composite cylinder, guided wave modes for anisotropic and composite cylinders are presented. Transient analysis of ultrasonic guided waves generated by concentrated heating of the outer surface of an infinite anisotropic cylinder has also been studied. The SAFE method is employed to model the response of a cylinder due to a pulsed laser focused on its surface. Green’s functions were constructed numerically by superposition of guided wave modes in frequency and wave number domains. Time histories of the propagating modes are then calculated by applying an inverse Fourier transformation in the time domain. Transient radial displacements of longitudinal and flexural modes of a silicon nitride cylinder are presented. Propagation of thermoelastic waves in finite length circular cylinders have also been investigated. The SAFE method is used to simulate the guided wave modes in the cylinder. Frequency spectra obtained by the SAFE formulation, for a finite length transversely isotropic cylinder, are validated by comparing the numerical results with relevant publications. Frequency spectra for axisymmetric and asymmetric modes in a silicon nitride finite cylinder with both ends insulated and restrained by frictionless rigid walls are presented. The plain strain problem of circumferential guided waves is also studied and the results are validated for an isothermal case.

Prostate cancer is the most common type of cancer afflicting Canadian men. Image-guided external radiation therapy of prostate cancer requires the accurate positioning of the patient in the treatment field. The alignment process is done using three fiducial markers implanted in the prostate. The current clinical practice involves the manual localization of these markers on pre-treatment, low-resolution electronic portal images (EPI). We propose an algorithm for the automatic detection of these markers. Our approach first enhances the quality of the EPI images using a fully automatic image enhancement approach. Next, fiducial markers are detected using template matching and a novel way of integrating information across multiple views. Experimental results show a significant improvement in the detection of fiducial markers in the left lateral view with respect to state-of-the-art results in related work. One should note that the left lateral view is the most challenging view due to the low resolution and the presence of occluding bony structures. / Graduate

This thesis involves modeling, guidance, control, and flight simulations of a canard controlled guided missile. The autopilot is designed by a pole placement technique. Designed autopilot is used with the guidance systems considered in the thesis. Five different guidance methods are applied in the thesis, one of which is the famous proportional navigation guidance. The other four guidance methods are different fuzzy logic guidance systems designed considering different types of guidance inputs. Simulations are done against five different target types and the performances of the five guidance methods are compared and discussed.