Design and evaluation of a continuous-wave diffuse optical tomography system.

Diffuse optical tomography (DOT) can image spatial variations in highly scattering optical media. We have built an inexpensive and portable continuous-wave DOT system containing 18 laser diode sources (9 at 780nm and 9 at 830nm) and 16 silicon detectors, which can acquire 288 independent measurements in less than 4 seconds. These data can then be processed using a variety of imaging algorithms. We first discuss the design of diffuse imaging equipment in general, and then describe our instrument, along with the technical issues that influenced its design. The technical challenges involved in performing DOT over large optode areas are discussed. We also present rat brain measurements following electrical forepaw stimulation using DOT. These results clearly demonstrate the capabilities of DOT and set the stage for advancement to quantitative functional brain imaging.