A semi-anthropomorphic breast phantom with tunable blood oxygenation levels for use in quantitative photoacoustics

Photoacoustic imaging is an upcoming technique with potential in breast cancer screening and diagnosis. It is able to visualize the breast's vasculature. Its quantitative counterpart, called quantitative photoacoustics, potentially enables the derivation of local blood oxygen saturations when two or more optical wavelengths are used. Tumors can potentially be detected by looking at abnormal vessel shapes, high vascular densities or regions with a low oxygenation. In order to obtain accurate oxygen saturation estimations with quantitative photoacoustics, realistic light propagation models are required. Several models are available, but it is difficult to check their validity on real breasts due to the unknown ground truths, while simple objects having known ground truths are known to overestimate the performance of the algorithms. Therefore, measurements on an object that mimics the breast both optically as well as acoustically, and which has a complex but known morphology, are therefore required. We have previously reported on the first semi-anthropomorphic photoacoustic-ultrasound breast phantom. In this work, we build further upon this to make it suitable for use in quantitative photoacoustics. We demonstrate a method to embed blood vessels and tumors into the phantom where blood with a controlled oxygenation level can be flushed through.