High performance time-resolved diffuse optical tomography system

Abstract

In this paper, we present a high performance time-resolved diffuse optical tomography (DOT) system whose working principle and implementation are very different from the conventional methods and features near real-time data acquisition. Dual-wavelength near-infrared light at 784 nm and 808 nm are used as light source. A high bit rate pseudo-random bit sequence (2.488 GB/s) modulates both continuous lights when they go through the external intensity modulator. The diffuse photon density waves responding to such modulated light are detected by array of high sensitivity, high speed silicon avalanche photodetectors (APD). The temporal point spread function can be retrieved very quickly by using hardware auto-/cross-correlation. Our system implementation has achieved system impulse with rise time approaching 0.5 ns which is highly desirable for time-domain DOT application to penetrate depth in few centimeters. The temporal resolution is mainly limited by the photodetectors. System performance is stabilized with accurate temperature control over key components. Experiment results based on tissue-like phantoms verify our design is potential for breast cancer imaging.