Tomographic Time-of-Flight Optical Imaging Device

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Abstract
Time-resolved optical imaging has been used to image phantoms, animals, and humans, and offers the potential for the production of functional images of human tissues, such as the oxygenation of brain during stroke. We had previously reported a transmission scanner, and now give an early report on conversion to a rotational tomographic scanner with a non-parallel ray geometry similar to early CAT scanners. Initial scans show that 1) spatial imaging in turbid media using time-of-flight measurements, non-recursive algorithms, and standard tomographic geometry is possible, 2) separation of absorbance and scattering as an image is attainable, a key step in performing spatially-resolved chemometric analysis, 3) imaging of multiple objects buried within scattering material is feasible, demonstrating that equations derived for homogeneous media can be applied in at least some cases to inhomogeneous media such as tissue-like phantoms, and 4) imaging of brain pathology produces recognizable images with sufficient resolution for diagnostic decisions. We conclude that optical tomography is feasible for clinical use and that conversion of the present mechanically scanning device to a clinical scanner should be possible with retention of the current processing algorithms. Such a clinical scanner should ultimately be able to generate images in a few minutes with centimeter resolution at the center of living human brain.