The rate at which women choose mastectomy has grown dramatically, and of particular note is the increase in contralateral prophylactic mastectomy (CPM). For women with no history of breast cancer or genetic risk, CPM represents a treatment decision that does not offer better long-term outcomes than the decision not to remove a healthy breast and may be associated with increased surgical risk and interventions, increased cost to the healthcare system, and potential adverse psycho-social outcomes. To better understand the decision making process regarding the election of CPM among women with early stage unilateral breast cancer, with no family history or genetic risk, a three-phase exploratory study was conducted. Qualitative in-depth interviews were conducted with healthcare providers who have close interaction with women during the decision making process (N=3) and patients who made a surgical decision about breast cancer treatment within the past three years (N=11). These two phases informed the design of the quantitative internet survey, conducted among women diagnosed with early stage breast cancer in the process of making a surgical decision (N=336). The survey design was also guided by an existing model for treatment decision making which uses a social ecological framework (Revenson & Pranikoff, 2005). In addition to descriptive analyses, perceptual mapping was utilized to understand patients’ conceptualizations of the relative importance of factors considered during the decision making process, and AdSAM® was used to gauge emotional response. Results suggest that women more likely to elect CPM demonstrate an emotional response to a generalized fear of cancer, along with the need to take control of their situation. In addition, retrospective interviews emphasized somewhat different reasons for electing CPM, highlighting the importance of prospective research in studying the decision making process. / Public Health

This thesis is concerned with maximizing the coding efficiency, random accessibility and visual performance of scalable compressed video. The unifying theme behind this work is the use of finely embedded localized coding structures, which govern the extent to which these goals may be jointly achieved. The first part focuses on scalable volumetric image compression. We investigate 3D transform and coding techniques which exploit inter-slice statistical redundancies without compromising slice accessibility. Our study shows that the motion-compensated temporal discrete wavelet transform (MC-TDWT) practically achieves an upper bound to the compression efficiency of slice transforms. From a video coding perspective, we find that most of the coding gain is attributed to offsetting the learning penalty in adaptive arithmetic coding through 3D code-block extension, rather than inter-frame context modelling. The second aspect of this thesis examines random accessibility. Accessibility refers to the ease with which a region of interest is accessed (subband samples needed for reconstruction are retrieved) from a compressed video bitstream, subject to spatiotemporal code-block constraints. We investigate the fundamental implications of motion compensation for random access efficiency and the compression performance of scalable interactive video. We demonstrate that inclusion of motion compensation operators within the lifting steps of a temporal subband transform incurs a random access penalty which depends on the characteristics of the motion field. The final aspect of this thesis aims to minimize the perceptual impact of visible distortion in scalable reconstructed video. We present a visual optimization strategy based on distortion scaling which raises the distortion-length slope of perceptually significant samples. This alters the codestream embedding order during post-compression rate-distortion optimization, thus allowing visually sensitive sites to be encoded with higher fidelity at a given bit-rate. For visual sensitivity analysis, we propose a contrast perception model that incorporates an adaptive masking slope. This versatile feature provides a context which models perceptual significance. It enables scene structures that otherwise suffer significant degradation to be preserved at lower bit-rates. The novelty in our approach derives from a set of "perceptual mappings" which account for quantization noise shaping effects induced by motion-compensated temporal synthesis. The proposed technique reduces wavelet compression artefacts and improves the perceptual quality of video.