Improving depth resolution of diffuse optical tomography with a layer-based sigmoid adjustment method.

Diffuse optical tomography (DOT) has much lower sensitivity in deep tissues than in superficial tissues, which leads to poor depth resolution. In this paper, a layer-based sigmoid adjustment (LSA) method is proposed for reducing sensitivity contrast in the depth dimension. Using this method, differences in image quality between layers can be effectively reduced. As a result, positioning errors of less than 3 mm can be obtained in the depth dimension for all depths from -1 cm to -3 cm.