Instrumentation of rapid near-infrared diffuse optical tomography for imaging of tissue at 35 frames per second

This paper presents the design, instrumentation, and performance of a rapid imaging near-infrared diffuse optical tomography system that is capable of collecting tomographic measurements at 35 frames per second. The video-rate tomographic data acquisition is achieved by spectral wavelength encoding of the sources, which allows many sources to be input into the tissue at the same time, followed by spectral-decoding of all detection channels in parallel using a spectrometer and CCD detector. The combination of spectral-decoding of the source lights horizontally in a spectrometer and spatial-separation of the detector positions vertically at the entrance slit provides continuous data for the entire set of source-detector pairs. A data acquisition speed of 35Hz frame rate was achieved with the use of the CCD operating in frame-transfer mode. The described system features 8 sources at an overall 785nm center band with average of 1.25nm spacing in wavelength and 8 detectors evenly deployed in a 27mm array designed for imaging with small animal tissues. The system's imaging characteristics as well as examples of capturing transient changes of absorption in the dynamic phantom are presented.