Optimizing ultrasound detection for sensitive 3D photoacoustic breast tomography

The standard modality for breast cancer detection is X-ray imaging. Diagnosis is performed after the triple assessment of X-ray mammography assisted by ultrasonog- raphy and biopsy. Magnetic resonance imaging (MRI) is sometimes used in specific problem solving such as contradictory results are obtained from X-ray and ultrasound images. X-ray mammography is capable of producing 2D projection images with a high spatial resolution. However, X-ray mammography besides possessing ionizing hazards, is less sensitive in women with dense breasts. In addition, X-ray mammography has difficulties to image tumors close to the chest wall. Ultrasonography still suffers from poor soft tissue contrast, inherent speckle noise, strong operator dependence and lack of standardization. MRI has high sensitivity but suffers from variable specificity, a relatively high cost and needs the use of a contrast agent. Thus there is a great need for an alternative technology to detect and diagnose early stages of breast cancer with high sensitivity and specificity. Photoacoustic (PA) imaging has shown great potential to visualize high optical absorption contrast based on hemoglobin absorption that can impact breast cancer detection and diagnosis. State-of-the-art photoacoustic breast imaging systems are promising but are limited either by only a 2D imaging capability or an insufficient imaging field-of-view (FOV) in 3D. This thesis investigates various aspects regarding the design and development of a sensitive 3D photoacoustic tomography system for full breast imaging, focusing on the optimization of ultrasound detection, the heart of the system