Design of a rotational ultrasound guided diffuse optical tomography system for whole breast imaging

This study focuses on a multimodal imaging technique that integrates both structural and functional information using a priori ultrasound (US) information to assist near-infrared (NIR) diffuse optical tomography (DOT). Up to date, hand-held systems that integrates DOT and US have been demonstrated. Our system is designed to be fully-automated and non-contact. Our aim is to build an interface, in which the optical source and detector fibers will rotate around the breast together with the US transducer. However, in this study we built a prototype system, which rotated the phantom and kept the transducers stationary for simplicity. Simulation and experimental studies were performed using a variety of source-detector configurations. The reconstruction results were compared with and without US a priori information. To collect the a priori US information, the multi-modality agar phantom was rotated 360 degrees using a computer controlled rotational stage. The multi-modality phantom had an inclusion that had both optical absorption and US contrast. 360 US images were collected in 1 degrees increments covering the entire phantom volume. The DOT data was also collected while the phantom is rotated with particular source-detector configurations. These results have shown that when the detectors were pi /8 apart, and the phantom is rotating at pi /16 increments with a total of 32 views provide the optimum image reconstruction. As expected, US a priori information further improved the quantification accuracy.