Photon density waves imaging with K-space spectrum analysis: clinical studies, background subtraction, and boundary effects

In recent years, a variety of techniques for imaging turbid media such as tissue with diffuse photon density waves (DPDW) have been explored. Most of these methods employ iterative techniques (e.g., ART, SIRT, and conjugate gradient) for image reconstruction, and they are in general computationally intensive. In this paper the authors use a recently developed imaging algorithm based on K-space spectral analysis. This technique is fast and noniterative. In addition to providing information about the position of hidden object(s), accurate optical properties of thin heterogeneities can be obtained when information about their depth is available. The authors believe they report here the first clinical image obtained by K-space spectrum analysis of DPDW measurements. In addition a new method for determining the background optical properties of an imaged sample and the influence of boundary conditions are discussed.