A new optical imaging system uses red and NIR light to identify breast cancer patients who may benefit most from chemotherapy. The dynamic diffuse optical tomography system could predict response to chemotherapy as early as two weeks after a patient begins treatment. The tomographic breast imaging system offers a non-invasive method of measuring blood flow dynamics in response to a single breath hold. The system generates 3D images of both breasts simultaneously, enabling researchers to look at blood flow in the breasts and see how the vasculature changes and how the blood interacts with the tumor.