| Breast cancer is the second leading cause of cancer-related deaths among American women. While it is generally agreed that screening mammography reduces the breast cancer death rate in women over forty years of age, some concern has been raised regarding mammography's performance. In particular, it has been suggested that as many as 50% of breast cancers present at the time of screening go undetected with film mammograms. To improve mammography's performance, conventional B-mode ultrasound can be used to supplement mammography for breast imaging. Ultrasound has proven useful for the detection of malignant lesions in premenopausal women with high breast density whose mammograms fail to provide sufficient radiographic contrast for lesion detection.;Despite the benefit of using ultrasound to augment mammography, several limitations of conventional ultrasound imaging can be identified in the context of breast cancer screening. With respect to image acquisition, a single B-mode ultrasound image only provides a tomographic scan of the breast at the position of the acoustic transducer. Thus, in order to acquire a conventional full-field breast ultrasound image, the transducer must be translated across the extent of the breast using fine indexing. Although the time required to perform these exams has been reduced through the development of automated breast ultrasound imaging systems, full-field scan times remain substantially longer than a mammogram acquisition. Furthermore, the radiologist must interpret a large number of B-mode images with this approach.;The research presented in this thesis involved an assessment of the diagnostic value of a prototype transmission ultrasound breast imaging system employing a novel acousto-optic (AO) liquid crystal ultrasonic detector. This system has the potential to address the limitations of conventional pulse-echo ultrasound by producing high-resolution, full-field ultrasound projection images of the compressed breast in a single acquisition. It is hoped that the system studied in this work can ultimately be integrated with mammography systems to allow for rapid acquisition of x-ray and ultrasound data in a single breast screening exam and subsequent image co-registration for easy interpretation and diagnosis by a radiologist. |
