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Conventional sonography, which performs well in dense breast tissue and is comfortable and radiation-free, is
not practical for screening because of its operator dependence and the time needed to scan the whole breast.
While magnetic resonance imaging (MRI) can significantly improve on these limitations, it is also not
practical because it has long been prohibitively expensive for routine use. There is therefore a need for an
alternative breast imaging method that obviates the constraints of these standard imaging modalities. The
lack of such an alternative is a barrier to dramatically impacting mortality (about 45,000 women in the US per
year) and morbidity from breast cancer because, currently, there is a trade-off between the cost effectiveness
of mammography and sonography on the one hand and the imaging accuracy of MRI on the other. This paper
presents a progress report on our long term goal to eliminate this trade-off and thereby improve breast cancer
survival rates and decrease unnecessary biopsies through the introduction of safe, cost-effective, operatorindependent
sonography that can rival MRI in accuracy.
The objective of the study described in this paper was to design and build an improved ultrasound
tomography (UST) scanner in support of our goals. To that end, we report on a design that builds on our
current research prototype. The design of the new scanner is based on a comparison of the capabilities of our
existing prototype and the performance needed for clinical efficacy. The performance gap was quantified by
using clinical studies to establish the baseline performance of the research prototype, and using known MRI
capabilities to establish the required performance. Simulation software was used to determine the basic
operating characteristics of an improved scanner that would provide the necessary performance. Design
elements focused on transducer geometry, which in turn drove the data acquisition system and the image
reconstruction engine specifications. The feasibility of UST established by our earlier work and that of other
groups, forms the rationale for developing a UST system that has the potential to become a practical, low-cost
device for breast cancer screening and diagnosis.
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