The study of the correlation between the radiological characteristics of the breast and the likelihood of the breast containing, or subsequently developing, a malignant lesion is termed breast density. In this thesis, a technique is developed for measuring the x-rav attenuation properties of breast tissue from an x-ray mammogram. The measure is independent of the characteristics and configuration of the x-ray equipment used to acquire the image. The intention is to provide a tool which facilitates the study of breast density by providing quantitative measurements of tissue characteristics, which it is hoped will ultimately form the basis of future risk estimation and malignant lesion diagnosis techniques. Part I of the thesis discusses the various area and volumetric measurements of breast density presented in the literature, together with the current hypotheses explaining the statistical results observed in epidemiological studies from a histopathological standpoint. The aim is to develop an inter-disciplinary understanding of the area under investigation to facilitate optimal development. A novel physics based model describing the complete process of mammographic image formation is presented in part II of the thesis. The design, build and test methodology executed for each component of the mammographic equipment is discussed through the chapters: the x-rav tube; the image receptor; and the anti-scatter grid. A ray tracing algorithm for computing the details of traversal paths is presented, as is an algorithm for calculating the scattered energy incident upon the image receptor. In each chapter, the underlying physical model is described, followed by the software design and implementation details, and finally the results of the experimental phantom validations studies to verify the implementation and underlying model. Where appropriate, sensitivity analysis is included so that uncertainty bounds may be estimated. Part III of the thesis proposes a novel measure of breast density, and describes how it overcomes the limitations of many existing techniques, in particular the Highnam and Brady 1996 hint model. The results of a clinical trial are included which demonstrate a favourable correlation between the proposed measure and the occurrence of malignancy compared to that observed using other methods.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:558699 |
| Date | January 2006 |
| Creators | Tromans, Christopher E. |
| Contributors | Brady, Michael |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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