Fast time-domain diffuse optical tomography using pseudorandom bit sequences

We report a novel time-domain diffuse optical tomography to determine the optical properties in a faster speed than the conventional ones. Instead of using the ultrashort pulse laser, a 2.5 Gbps pseudorandom bit sequence is used to modulate the near-infrared light for tissue-like phantom illumination. The time-resolved signal can be retrieved very quickly by demodulation with the reference signal. The system impulse response has a full width at half maximum around 800 picoseconds and the 2-dimentional maps of optical properties can be obtained within a few seconds. The high signal-to-noise ratio and the environmental illumination insensitivity warrant a great potential for applications in clinical noninvasive breast cancer detection.