The long term objective of the proposed program is to develop Acoustography, a new imaging method, to aid in the detection and characterization of breast cancer. Acoustography uses ultrasound to produce full-field projection images of the breast in a manner which is analogous to x-ray mammography. An "acousto-optical" liquid crystal display, analogous to a fluoroscopic screen, is used to visualize and record the ultrasonic image of the entire breast. The specific aim in Phase I will be to use breast phantoms to evaluate Acoustography. Tissue mimicking materials currently used for producing phantoms to evaluate conventional ultrasonography equipment will be used to produce breast phantoms suitable for acoustographic studies. Commercially, Acoustography offers physicians a much more practical way of generating ultrasonic images because the entire breast can be imaged with only one or two images, and the image format allows direct side-by-side comparison of the ultrasonic and x-ray breast images. Compared to general-purpose scanners, Acoustography is more repeatable because the procedure can be standardized similarly to an x-ray mammography. Compared to dedicated scanners, Acoustography is cost-effective and offers high patient throughput; the entire breast information is available in seconds on 1 or 2 images, as opposed to 100-150 images in dedicated scanners.