Thermoacoustic and Inverse Scattering Breast Cancer Scanner ABSTRACT: We propose a novel, hybrid, imaging system for breast cancer diagnosis that exploits the elevated electrical conductivity. This system combines three advanced ultrasound- imaging methods with thermoacoustic imaging. The new ultrasound imaging methods are: (1) a reflection ultrasound tomography modality (images acoustic impedance gradients); (2,) an ultrasound inverse scattering modality that image absolute speed of sound); (3) an ultrasound inverse scattering modality that images absolute acoustic absorption). The fourth modality is: (4) a new, advanced, thermoacoustic imaging modality, which images electrical conductivity at higher spatial resolution than heretofore possible and allows the discrimination of cancer vs. fibroadenoma (which mammography and present clinical ultrasound distinguish poorly). The first modality provides improved imaging over standard clinical ultrasound because of its: uniform high spatial resolution (B-scan resolving power falls of inversely with range), operator independence, true 3-D images, improved contrast resolution and correction for refraction and absorption. The second and third modalities provide the advanced features given by the first, plus: perfect spatial registration; absolution quantitative rendering of tissue sound speed and absorption coefficient; elimination of multiple scattering artifacts and speckle; and potential for improved resolution to one half wavelength. The combination of four modes synergistically improves diagnosis and screening. The fourth modality is improved by making amplitude and phase corrections derived from the second and third modalities. One in every 7 women will develop breast cancer in her lifetime. However, present diagnostic specificity for cancer detection (using mammography) is poor, with 3 in 4 biopsies yielding benign tissue. This proposal, which combines two novel techniques for breast cancer detection?namely Thermoacoustic Emission and Ultrasound Inverse Scattering?has a tremendous potential for improving breast cancer detection. [unreadable] [unreadable] [unreadable]