Spatial resolved diffuse reflection as a tool for determination of size and embedding depth of blood vessels

Spatial resolved diffuse reflectance signals were obtained by Monte Carlo simulation from a cylindrical vessel filled with a suspension of particles mimicking the nonaggregating erythrocytes. The vessel is embedded in a scattering medium with optical properties close to those of human skin. It is shown that due to strong absorption and scattering properties of the blood, a decrease in reflected radiation is maximal directly over the embedded cylinder. This feature makes the technique potentially useful for imaging and sizing the blood vessels. It is also shown that the image blur increases next to linearly with the increase in blood vessel embedding depth. This feature can be used for determining the latter for the vessels with fixed radii and fixed optical properties of the surrounding medium. The optimal position for the laser probe yielding the highest image quality was found.