Sensitivity Matrix Implementation in the Monte Carlo Package MBioICFO for the Simulation of Photon Migration in Tissues

Abstract

An extension of the Monte Carlo method in diffuse optics was developed. Diffuse optical technology measures light absorption and scattering in human tissue. A sensitivity matrix has to be constructed to obtain structural information. It contains the sensitivities of the detected signal to absorption or scattering changes in different regions of the tissue. The existing MBioICFO simulation package was extended to allow the construction of the sensitivity matrix for perturbations in absorption. As opposed to prior implementations, the sensitivity matrix is determined in one simulation run and for arbitrary geometries. The new method was verified with analytical solutions for homogeneous media with infinite and semiinfinite boundary conditions. The method also enables determination of the sensitivity matrix for different detection times and in geometries obtained from MRI measurements. The program has shown appropriate computational efficiency with acceptable runtimes.