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The role of physics testing in breast cancer screening

Martinez, L. J. (1995). The role of physics testing in breast cancer screening. (Unpublished Doctoral thesis, City, University of London)


The aim of the work contained in this thesis is to critically evaluate the role of quality assurance testing on equipment used within the breast screening programme in the UK. At the time the work began, mass screening had only just started in the UK, and, although many countries had breast screening projects of one form or another, no-one else was attempting to screen the whole population. The X-ray equipment was totally new, having been re-designed in line with the specifications from the Department of Heath [1], and it was far from certain that the quality assurance procedures recommended were the most appropriate or the most cost-effective for this particular branch of imaging.

Chapter one discusses the evidence and rationale for doing breast screening at all. The range of available screening techniques is described and their potential benefits for breast screening are discussed. Strategies for screening are also examined and a mathematical model to relate the benefit of screening to rate of cancer growth and screening interval has been developed. Breast screening programmes both in the UK and abroad are reviewed.

In chapter two a statistical description of screening in North East Thames is presented and using real statistics as the starting point, a computer model has been developed which uses three levels of Bayesian likelihood analysis to represent the screening, assessment and biopsy stages. Sensitivity of the cancer detection rate and number of missed cancers to variations in uptake, image quality and decision criteria is analysed particularly to show how important image quality is to the final outcome of the screening process. The procedures for physical quality assurance are described.

Chapter three contains analysis of the gathered data from X-ray equipment and finds that the X-ray tube output is a key indicator of tube condition. The minimum period of time at which such changes are detectable is calculated.

Chapter four examines the role of the film processor and analyses the key sources of variation in processing.

Chapter five takes the results from the previous two chapters and uses them to build a new scheme of quality assurance which provides more information and better analysis for less effort. A financial analysis has been done comparing the new and old systems.

Chapter six concludes that breast screening QA can improve the effectiveness of screening and concludes that the scheme developed in this work enables it to be done more cheaply and efficiently. Areas which are unresolved by this project are identified and further work is suggested.

Publication Type: Thesis (Doctoral)
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
R Medicine > RZ Other systems of medicine
Departments: School of Science & Technology > Computer Science
School of Science & Technology > School of Science & Technology Doctoral Theses
Doctoral Theses
[thumbnail of Martinez thesis 1995 PDF-A.pdf]
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