Diffuse optical tomography (DOT) is an effective tool for imaging biological tissues. Comparing to other imaging methods, DOT has better temporal resolution and lower instrumental cost. However, DOT has some disadvantages such as limited imaging region and poor depth resolution. This paper focuses on overcoming the disadvantages of DOT. This will benefit its clinical applications. In recent two years, the multicentered mode has been proposed for improving the spatial resolution of DOT. However, the hexagon shaped multicentered mode has limited imaging region. To image adult human brain, we must expand the imaging region of the multicentered mode. In this paper, we proposed a pentagon shaped multicentered mode. Furthermore, we connected hexagons and pentagons to form a full-brain headgear. The poor depth resolution is another shortcoming of DOT. This is mainly because that photons lose there energies sharply as they propagate longer distance. In this paper, we proposed a layer-based sigmoid adjustment (LSA) method. The LSA method multiplies larger coefficients on deep tissues and multiplies smaller coefficients on superficial tissues, so the photon sensitivity contrast can be effectively reduced. In this paper, we implemented the LSA method in brain imaging. The results from simulations and human subject experiments showed that the depth resolution of the reconstructed images had been improved. In images reconstructed by LSA method, the activations are properly located on cerebral cortex and different activations can be observed for finger-moving and finger-tapping experiments. However, in images reconstructed without the LSA method, activations are biased to superficial layers and difference in activations can be hardly seen. Another important field DOT can be used in is breast imaging. In breast imaging, the poor depth resolution of DOT can cause large noise in reconstructed images. The results from simulations showed that by using the LSA method, noises in reconstructed images could be effectively reduced. With the LSA method, DOT can detect smaller and earlier tumor. This will benefit the clinical application of DOT.
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